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<h6 id="header">RMagick 2.1.0 User's Guide and Reference</h6>
<div class="nav">
« <a href="image2.html">Prev</a> | <a href=
"index.html">Contents</a> | <a href=
"draw.html">Next</a> »
</div>
<h1>class Image <span class="superclass">< Object</span>
(instance methods p-w)<br />
<span class="mixin">mixes in Comparable</span></h1>
<div id="toc">
<h2>Table of Contents</h2>
<h3>instance methods</h3>
<div>
<div class="toccol">
<ul>
<li><a href="#palette_q">palette?</a></li>
<li><a href="#pixel_color">pixel_color</a></li>
<li><a href="#polaroid">polaroid</a></li>
<li><a href="#posterize">posterize</a></li>
<li><a href="#preview">preview</a></li>
<li><a href="#profile_bang">profile!</a></li>
<li><a href="#properties">properties</a></li>
<li><a href="#quantize">quantize</a></li>
<li><a href="#quantum_operator">quantum_operator</a></li>
<li><a href="#radial_blur">radial_blur</a></li>
<li><a href=
"#radial_blur_channel">radial_blur_channel</a></li>
<li><a href="#raise">raise</a></li>
<li><a href=
"#random_threshold_channel">random_threshold_channel</a></li>
<li><a href="#recolor">recolor</a></li>
<li><a href="#reduce_noise">reduce_noise</a></li>
<li><a href="#resample">resample</a></li>
<li><a href="#resize">resize</a></li>
<li><a href="#resize_bang">resize!</a></li>
<li><a href="#resize_to_fill">resize_to_fill</a></li>
<li><a href=
"#resize_to_fill_bang">resize_to_fill!</a></li>
<li><a href="#resize_to_fit">resize_to_fit</a></li>
<li><a href="#resize_to_fit_bang">resize_to_fit!</a></li>
<li><a href="#roll">roll</a></li>
<li><a href="#rotate">rotate</a></li>
<li><a href="#rotate_bang">rotate!</a></li>
</ul>
</div>
<div class="toccol">
<ul>
<li><a href="#sample">sample</a></li>
<li><a href="#sample_bang">sample!</a></li>
<li><a href="#scale">scale</a></li>
<li><a href="#scale_bang">scale!</a></li>
<li><a href="#segment">segment</a></li>
<li><a href="#separate">separate</a></li>
<li><a href="#sepiatone">sepiatone</a></li>
<li><a href=
"#set_channel_depth">set_channel_depth</a></li>
<li><a href="#shade">shade</a></li>
<li><a href="#shadow">shadow</a></li>
<li><a href="#sharpen">sharpen</a></li>
<li><a href="#sharpen_channel">sharpen_channel</a></li>
<li><a href="#shave">shave</a></li>
<li><a href="#shave_bang">shave!</a></li>
<li><a href="#shear">shear</a></li>
<li><a href=
"#sigmoidal_contrast_channel">sigmoidal_contrast_channel</a></li>
<li><a href="#signature">signature</a></li>
<li><a href="#sketch">sketch</a></li>
<li><a href="#solarize">solarize</a></li>
<li><a href="#splice">splice</a></li>
<li><a href="#spread">spread</a></li>
<li><a href="#stegano">stegano</a></li>
<li><a href="#stereo">stereo</a></li>
<li><a href="#store_pixels">store_pixels</a></li>
<li><a href="#strip_bang">strip!</a></li>
</ul>
</div>
<div class="toccol">
<ul>
<li><a href="#swirl">swirl</a></li>
<li><a href="#sync_profiles">sync_profiles</a></li>
<li><a href=
"#texture_fill_to_border">texture_fill_to_border</a></li>
<li><a href=
"#texture_floodfill">texture_floodfill</a></li>
<li><a href="#threshold">threshold</a></li>
<li><a href="#thumbnail">thumbnail</a></li>
<li><a href="#thumbnail_bang">thumbnail!</a></li>
<li><a href="#to_blob">to_blob</a></li>
<li><a href="#to_color">to_color</a></li>
<li><a href="#transparent">transparent</a></li>
<li><a href="#transpose">transpose</a></li>
<li><a href="#transpose_bang">transpose!</a></li>
<li><a href="#transverse">transverse</a></li>
<li><a href="#transverse_bang">transverse!</a></li>
<li><a href="#trim">trim</a></li>
<li><a href="#trim_bang">trim!</a></li>
<li><a href="#unique_colors">unique_colors</a></li>
<li><a href="#unsharp_mask">unsharp_mask</a></li>
<li><a href=
"#unsharp_mask_channel">unsharp_mask_channel</a></li>
<li><a href="#view">view</a></li>
<li><a href="#vignette">vignette</a></li>
<li><a href="#watermark">watermark</a></li>
<li><a href="#wave">wave</a></li>
<li><a href="#wet_floor">wet_floor</a></li>
<li><a href="#white_threshold">white_threshold</a></li>
<li><a href="#write">write</a></li>
</ul>
</div>
</div>
</div>
<h2 class="methods">instance methods</h2>
<div class="sig">
<h3 id="palette_q">palette?</h3>
<p><span class="arg">img</span>.palette? -> true or
false</p>
</div>
<div class="desc">
<h4>Description</h4>
<p class="imquote">Returns true if the image is <a href=
"constants.html#ClassType">PseudoClass</a> and has 256 unique
colors or less.</p>
<h4>Returns</h4>
<p>true or false</p>
<h4>Magick API</h4>
<p>IsPaletteImage</p>
</div>
<div class="sig">
<h3 id="pixel_color">pixel_color</h3>
<p><span class="arg">img</span>.pixel_color(<span class=
"arg">x</span>, <span class="arg">y</span>[, <span class=
"arg">new_color</span>]) -> <em>pixel</em></p>
</div>
<div class="desc">
<h4>Description</h4>
<p>Returns the color of the pixel at <span class=
"arg">x</span>, <span class="arg">y</span>. Optionally, changes
the color of the pixel to a new color.</p>
<p>If new_color is specified, pixel_color changes the image
type to DirectClass if necessary.</p>
<h4>Arguments</h4>
<dl>
<dt>x, y</dt>
<dd>The x- and y-coordinates of the pixel.</dd>
<dt>new_color</dt>
<dd>If specified, the pixel is set to this color. May be
either a <a href="imusage.html#color_names">color name</a> or
a <a href="struct.html#Pixel">Pixel</a>.</dd>
</dl>
<h4>Returns</h4>A <a href="struct.html#Pixel">Pixel</a> having
the RGB values of the specified pixel.
<h4>Example</h4>
<pre>
old = image.pixel_color(20,40,"white")
</pre>
<h4>Magick API</h4>
<p>AcquireImagePixels</p>
</div>
<div class="sig">
<h3 id="polaroid">polaroid</h3>
<p><span class="arg">img</span>.polaroid(angle=-5.0) [
<span class="arg">{ optional arguments }</span> ] ->
image</p>
</div>
<div class="desc">
<h4>Description</h4>
<p>Produce an image that looks like a Polaroid® instant
picture. If the image has a "Caption" <a href=
"image1.html#aset">property</a>, the value is used as a
caption.</p>
<p>Optional arguments may be specified in a block associated
with the method. These arguments control the shadow color and
how the label is rendered. By default the shadow color is
gray75. To specify a different shadow color, use
<code>self.shadow_color</code>. To specify a different border
color (that is, the color of the image border) use
<code>self.border_color</code>. Both of these methods accept
either a <a href="imusage.html#color_names">color name</a> or a
<a href="struct.html#Pixel">Pixel</a> argument.</p>
<p>The following <a href="draw.html#annotate">annotate</a>
attributes control the label rendering: <a href=
"draw.html#align_eq">align</a>, <a href=
"draw.html#decorate_eq">decorate</a>, <a href=
"draw.html#density_eq">density</a>, <a href=
"draw.html#encoding_eq">encoding</a>, <a href=
"draw.html#fill_eq">fill</a>, <a href=
"draw.html#font_eq">font</a>, <a href=
"draw.html#font_family_eq">font_family</a>, <a href=
"draw.html#font_stretch_eq">font_stretch</a>, <a href=
"draw.html#font_style_eq">font_style</a>, <a href=
"draw.html#font_weight_eq">font_weight</a>, <a href=
"draw.html#gravity_eq">gravity</a>, <a href=
"draw.html#pointsize_eq">pointsize</a>, <a href=
"draw.html#stroke_eq">stroke</a>, <a href=
"draw.html#stroke_width_eq">stroke_width</a>, <a href=
"draw.html#text_antialias_eq">text_antialias</a>, <a href=
"draw.html#undercolor_eq">undercolor</a>.</p>
<pre>
img.polaroid do
self.shadow_color = "gray40"
self.pointsize = 12
end
</pre>
<h4>Arguments</h4>
<dl>
<dt>angle</dt>
<dd>The resulting image is rotated by this amount, measured
in degrees. The default is -5.0.</dd>
</dl>
<h4>Example</h4>
<p><a href="javascript:popup('polaroid.rb.html')"><img src=
"ex/polaroid.jpg" alt="polaroid example" /></a></p>
<h4>Magick API</h4>
<p>PolaroidImage</p>
<h4>See also</h4>
<p><a href=
"http://rmagick.rubyforge.org/Polaroid/polaroid.html">The
Polaroid Effect</a></p>
<h4>Notes</h4>
<p>"Polaroid" and the other names of products of Polaroid
Corporation are trademarks of Polaroid Corporation.</p>
</div>
<div class="sig">
<h3 id="posterize">posterize</h3>
<p><span class="arg">img</span>.posterize(<span class=
"arg">levels</span>=4, <span class="arg">dither</span>=false)
-> <em>image</em></p>
</div>
<div class="desc">
<h4>Description</h4>
<p class="imquote">Reduces the image to a limited number of
colors for a "poster" effect.</p>
<h4>Arguments</h4>
<dl>
<dt>levels</dt>
<dd><span class="imquote">Number of color levels allowed in
each channel. Very low values (2, 3, or 4) have the most
visible effect.</span> The default is 4.</dd>
<dt>dither</dt>
<dd>If true, dither the image. The default is false.</dd>
</dl>
<h4>Returns</h4>
<p>A new image</p>
<h4>Example</h4>
<p class="rollover"><a href=
"javascript:popup('posterize.rb.html')"><img src=
"ex/posterize.jpg" alt="posterize example" onmouseover=
"this.src='ex/images/Flower_Hat.jpg'" onmouseout=
"this.src='ex/posterize.jpg'" title=
"Click to see the example script" /></a> <img src=
"ex/images/spin.gif" alt="" class="spin" title=
"Mouse over the example to see the original image" /></p>
<h4>See also</h4>
<p><a href="image2.html#ordered_dither">ordered_dither</a>,
<a href="image3.html#quantize">quantize</a></p>
<h4>Magick API</h4>
<p>PosterizeImage</p>
</div>
<div class="sig">
<h3 id="preview">preview</h3>
<p><span class="arg">img</span>.preview(<span class=
"arg">aPreviewType</span>) -> <em>image</em></p>
</div>
<div class="desc">
<h4>Description</h4>
<p>Creates an image that contains 9 small versions of the
receiver image. The center image is the unchanged receiver. The
other 8 images are variations created by transforming the
receiver according to the specified preview type with varying
parameters.</p>
<p>A preview image is an easy way to "try out" a transformation
method.</p>
<h4>Arguments</h4>
<p>One of the following PreviewType constants:</p>
<div id="prevlist">
<ul>
<li>RotatePreview</li>
<li>ShearPreview</li>
<li>RollPreview</li>
<li>HuePreview</li>
<li>SaturationPreview</li>
<li>BrightnessPreview</li>
<li>GammaPreview</li>
<li>SpiffPreview</li>
<li>DullPreview</li>
<li>GrayscalePreview</li>
<li>QuantizePreview</li>
<li>DespecklePreview</li>
<li>ReduceNoisePreview</li>
<li>AddNoisePreview</li>
<li>SharpenPreview</li>
</ul>
<ul>
<li>BlurPreview</li>
<li>ThresholdPreview</li>
<li>EdgeDetectPreview</li>
<li>SpreadPreview</li>
<li>SolarizePreview</li>
<li>ShadePreview</li>
<li>RaisePreview</li>
<li>SegmentPreview</li>
<li>SwirlPreview</li>
<li>ImplodePreview</li>
<li>WavePreview</li>
<li>OilPaintPreview</li>
<li>CharcoalDrawingPreview</li>
<li>JPEGPreview</li>
</ul>
</div>
<div style="clear:both"></div>
<h4>Returns</h4>
<p>A new image</p>
<h4>Example</h4>
<p>This half-size preview demonstrates the SolarizePreview
argument.</p>
<p><a href="javascript:popup('preview.rb.html')"><img src=
"ex/preview.jpg" alt="preview example" title=
"Click to see the example script" /></a></p>
<h4>Magick API</h4>
<p>PreviewImage</p>
</div>
<div class="sig">
<h3 id="profile_bang">profile!</h3>
<p><span class="arg">img</span>.profile!(<span class=
"arg">name</span>, <span class="arg">profile</span>) ->
<em>self</em></p>
</div>
<div class="desc">
<h4>Description</h4>
<p><span class="imquote">Adds or removes a ICM, IPTC, or
generic profile from an image.</span> If <code>profile</code>
is <code>nil</code>, the specified profile is removed from the
image. Use <code>profile('*', nil)</code> to remove all
profiles from the image.</p>
<h4>Arguments</h4>
<dl>
<dt>name</dt>
<dd>The profile name, or "*" to represent all the profiles in
the image.</dd>
<dt>profile</dt>
<dd>The profile value, or <code>nil</code> to cause the
profile to be removed.</dd>
</dl>
<h4>Returns</h4>
<p>self</p>
<h4>See also</h4>
<p><a href="image1.html#add_profile">add_profile</a> and
<a href="image1.html#delete_profile">delete_profile</a> perform
very similar functions. However, <code>add_profile</code>
accepts the name of a profile file on disk instead of the
profile data itself and, if the file contains more than one
profile, will load all the profiles at once.</p>
<h4>Magick API</h4>
<p>ProfileImage</p>
<h4>Notes</h4>
<p>ImageMagick does not automatically remove profiles when
resizing images. If you are trying to make your JPEG thumbnail
images as small as possible, use <code>profile!</code> to
remove any profiles from the image as well. Also see <a href=
"#strip_bang">strip!</a></p>
</div>
<div class="sig">
<h3 id="properties">properties</h3>
<p><span class="arg">img</span>.properties <span class="arg">[
{|name,value| block} ]</span> -> <em>hash</em></p>
</div>
<div class="desc">
<h4>Description</h4>
<p>If called with an associated block, <code>properties</code>
runs the block once for each property defined for the image.
The block arguments are the property name and its value. If
there is no block, <code>properties</code> returns a hash with
one element for each property. The hash key is the property
name and the associated value is the property value.</p>
<h4>Returns</h4>
<p>If called without a block, returns a hash, otherwise returns
<code>self</code>.</p>
<h4>See also</h4>
<p><a href="image1.html#aref">[ ]</a>, <a href=
"image1.html#aset">[ ]=</a></p>
<h4>Note</h4>
<p>The EXIF property is not created until the first time an
EXIF tag or entry number is referenced.</p>
</div>
<div class="sig">
<h3 id="quantize">quantize</h3>
<p><span class="arg">img</span>.quantize(<span class=
"arg">number_colors</span>=256, <span class=
"arg">colorspace</span>=RGBColorspace, <span class=
"arg">dither</span>=<code>true</code>, <span class=
"arg">tree_depth</span>=0, <span class=
"arg">measure_error</span>=<code>false</code>) ->
<em>image</em></p>
</div>
<div class="desc">
<h4>Description</h4>
<p class="imquote">Analyzes the colors within a reference image
and chooses a fixed number of colors to represent the image.
The goal of the algorithm is to minimize the difference between
the input and output image while minimizing the processing
time.</p>
<h4>Arguments</h4>
<dl>
<dt>number_colors</dt>
<dd>The maximum number of colors in the result image. Must be
<= <a href=
"constants.html#Miscellaneous_constants">QuantumRange</a>.</dd>
<dt>colorspace</dt>
<dd class="imquote">The <a href=
"constants.html#ColorspaceType">colorspace</a> to quantize
in. Color reduction, by default, takes place in the RGB color
space. Empirical evidence suggests that distances
in color spaces such as YUV or YIQ correspond
to perceptual color differences more closely
than do distances in RGB space. The Transparent color
space behaves uniquely in that it preserves the matte channel
of the image if it exists.</dd>
<dt>dither</dt>
<dd>Set to <code>false</code> to disable dithering. See the
documentation for the <a href=
"http://redux.imagemagick.org/script/command-line-options.php#dither">
ImageMagick -dither option</a> for more information.</dd>
<dt>tree_depth</dt>
<dd><span class="imquote">The tree depth to use while
quantizing. The values 0 and 1 support automatic tree depth
determination. The tree depth may be forced via values
ranging from 2 to 8. The ideal tree depth depends on the
characteristics of the input image, and may be determined
through experimentation.</span> See the documentation for the
<a href=
"http://redux.imagemagick.org/script/command-line-options.php#treedepth">
ImageMagick -treedepth option</a> for more information.</dd>
<dt>measure_error</dt>
<dd class="imquote">Set to <code>true</code> to calculate
quantization errors when quantizing the image.</dd>
</dl>
<h4>Returns</h4>
<p>A new image</p>
<h4>Example</h4>
<p>See the example for <a href=
"image1.html#colorize">colorize</a>.</p>
<h4>See also</h4>
<p><a href="image2.html#ordered_dither">ordered_dither</a>,
<a href="image3.html#posterize">posterize</a>, <a href=
"ilist.html#quantize">ImageList#quantize</a></p>
<h4>Magick API</h4>
<p>QuantizeImage</p>
</div>
<div class="sig">
<h3 id="quantum_operator">quantum_operator</h3>
<p><span class="arg">img</span>.quantum_operator(<span class=
"arg">operator</span>, <span class="arg">rvalue</span>,
<span class="arg">channel</span>=AllChannels) ->
<em>self</em></p>
</div>
<div class="desc">
<h4>Description</h4>
<p>Performs the requested integer arithmetic operation on the
selected channel of the image. This method allows simple
arithmetic operations on the component values of all pixels in
an image. Of course, you could also do this in Ruby using
<a href="image2.html#get_pixels">get_pixels</a> and <a href=
"#store_pixels">store_pixels</a>, or <a href="#view">view</a>,
but <code>quantum_operator</code> will be faster, especially
for large numbers of pixels, since it does not need to convert
the pixels from C to Ruby.</p>
<h4>Arguments</h4>
<dl>
<dt>operator</dt>
<dd>
One of the following <code>QuantumExpressionOperator</code>
constants:
<ul id="quantum_op_list">
<li>AddQuantumOperator</li>
<li><code>AndQuantumOperator</code></li>
<li><code>DivideQuantumOperator</code></li>
<li><code>LShiftQuantumOperator</code></li>
<li><code>MaxQuantumOperator</code></li>
<li><code>MinQuantumOperator</code></li>
<li><code>MultiplyQuantumOperator</code></li>
<li><code>OrQuantumOperator</code></li>
<li><code>RShiftQuantumOperator</code></li>
<li><code>SubtractQuantumOperator</code></li>
<li><code>XorQuantumOperator</code></li>
</ul>
</dd>
<dt>rvalue</dt>
<dd>a <code>Numeric</code> operation rvalue.</dd>
<dt>channel</dt>
<dd>A <a href="constants.html#ChannelType">ChannelType</a>
value. The default is to operate on all channels.</dd>
</dl>
<h4>Returns</h4>
<p>self</p>
<h4>Example</h4>
<p>Divide the red component of all the pixels in the image by
2:</p>
<pre>
img.quantum_operator(DivideQuantumOperator, 2, RedChannel)
</pre>
<h4>See also</h4>
<p>The <a href="struct.html#view">Image:View</a> class supports
operations on individual pixels and collections of pixels, as
well as operations on channels within pixels. See <a href=
"#view">view</a>, below.</p>
<h4>Magick API</h4>
<p>EvaluateImageChannel</p>
</div>
<div class="sig">
<h3 id="radial_blur">radial_blur</h3>
<p><span class="arg">img</span>.radial_blur(<span class=
"arg">float</span>) -> <em>image</em></p>
</div>
<div class="desc">
<h4>Description</h4>
<p class="imquote">Applies a radial blur to the image.</p>
<h4>Arguments</h4>
<dl>
<dt>angle</dt>
<dd>Amount of blur, in degrees</dd>
</dl>
<h4>Returns</h4>
<p>A new image</p>
<h4>Example</h4>
<p class="rollover"><a href=
"javascript:popup('radial_blur.rb.html')"><img src=
"ex/radial_blur.jpg" onmouseover=
"this.src='ex/images/Flower_Hat.jpg'" onmouseout=
"this.src='ex/radial_blur.jpg'" alt="radial_blur example"
title="Click to see the example script" /></a> <img src=
"ex/images/spin.gif" alt="" class="spin" title=
"Mouse over the example to see the original image" /></p>
<h4>See also</h4>
<p><a href="image1.html#blur_image">blur_image</a>, <a href=
"image2.html#gaussian_blur">gaussian_blur</a>, <a href=
"image2.html#motion_blur">motion_blur</a>, <a href=
"#radial_blur_channel">radial_blur_channel</a></p>
<h4>Magick API</h4>
<p>RadialBlurImage</p>
</div>
<div class="sig">
<h3 id="radial_blur_channel">radial_blur_channel</h3>
<p><span class=
"arg">img</span>.radial_blur_channel(<span class="arg">float</span>
[, <span class="arg">channel</span>...]) ->
<em>image</em></p>
</div>
<div class="desc">
<h4>Description</h4>
<p>Applies a radial blur to the selected image channels.</p>
<h4>Arguments</h4>
<dl>
<dt>angle</dt>
<dd>Amount of blur, in degrees</dd>
<dt>channel...</dt>
<dd>0 or more <a href=
"constants.html#ChannelType">ChannelType</a> arguments. If no
channels are specified, all the channels are blurred.</dd>
</dl>
<h4>Returns</h4>
<p>A new image</p>
<h4>See also</h4>
<p><a href="#radial_blur">radial_blur</a></p>
<h4>Magick API</h4>
<p>RadialBlurImageChannel</p>
</div>
<div class="sig">
<h3 id="raise">raise</h3>
<p><span class="arg">img</span>.raise(<span class=
"arg">width</span>=6, <span class="arg">height</span>=6,
<span class="arg">raised</span>=<code>true</code>) ->
<em>image</em></p>
</div>
<div class="desc">
<h4>Description</h4>
<p class="imquote">Creates a simulated three-dimensional
button-like effect by lightening and darkening the edges of the
image.</p>
<h4>Arguments</h4>
<dl>
<dt>width</dt>
<dd>The width of the raised edge in pixels. The default is
6.</dd>
<dt>height</dt>
<dd>The height of the raised edge in pixels. The default is
6.</dd>
<dt>raised</dt>
<dd>If <code>true</code>, the image is raised, otherwise
lowered.</dd>
</dl>
<h4>Returns</h4>
<p>A new image</p>
<h4>Example</h4>
<p class="rollover"><a href=
"javascript:popup('raise.rb.html')"><img src="ex/raise.jpg"
onmouseover="this.src='ex/images/Flower_Hat.jpg'" onmouseout=
"this.src='ex/raise.jpg'" alt="raise example" title=
"Click to see the example script" /></a> <img src=
"ex/images/spin.gif" alt="" class="spin" title=
"Mouse over the example to see the original image" /></p>
<h4>Magick API</h4>
<p>RaiseImage</p>
</div>
<div class="sig">
<h3 id="random_threshold_channel">random_threshold_channel</h3>
<p><span class="arg">img</span>.random_threshold_channel(
<span class="arg">thresholds</span>, [<span class=
"arg">channel</span>...] ) -> <em>image</em></p>
</div>
<div class="desc">
<h4>Description</h4>
<p class="imquote">Changes the value of individual pixels based
on the intensity of each pixel compared to a random threshold.
The result is a low-contrast, two color image.</p>
<h4>Arguments</h4>
<dl>
<dt>thresholds</dt>
<dd><span class="imquote">A geometry string containing
LOWxHIGH thresholds.</span> The string is in the form `XxY'.
The Y value may be omitted, in which case it is assigned the
value QuantumRange-X. If an % appears in the string then the
values are assumed to be percentages of QuantumRange.
<span class="imquote">If the string contains 2x2, 3x3, or
4x4, then an ordered dither of order 2, 3, or 4 will be
performed instead.</span> A <a href=
"struct.html#Geometry">Geometry</a> object may be used as
well.</dd>
<dt>channel...</dt>
<dd>0 or more <a href=
"constants.html#ChannelType">ChannelType</a> arguments. If no
channels are specified, all the channels are
thresholded.</dd>
</dl>
<h4>Returns</h4>
<p>A new image</p>
<h4>Example</h4>
<pre>
geom = Geometry.new(QuantumRange/2)
random_threshold_channel(geom, RedChannel)
</pre>
<p class="rollover"><a href=
"javascript:popup('random_threshold_channel.rb.html')"><img src="ex/random_threshold_channel.jpg"
alt="random_threshold_channel example" title=
"Click to see the example script" onmouseover=
"this.src='ex/images/Flower_Hat.jpg'" onmouseout=
"this.src='ex/random_threshold_channel.jpg'" /></a> <img src=
"ex/images/spin.gif" alt="" class="spin" title=
"Mouse over the example to see the original image" /></p>
<h4>See also</h4>
<p><a href=
"image1.html#adaptive_threshold">adaptive_threshold</a>,
<a href="image1.html#bilevel_channel">bilevel_channel</a>,
<a href="#threshold">threshold</a></p>
<h4>Magick API</h4>
<p>RandomThresholdImageChannel</p>
</div>
<div class="sig">
<h3 id="recolor">recolor</h3>
<p><span class="arg">img</span>.recolor(<span class=
"arg">color_matrix</span>) -> <em>image</em></p>
</div>
<div class="desc">
<h4>Description</h4>
<p>Use this method to <span class="imquote">translate, scale,
shear, or rotate image colors. Although you can use variable
sized matrices, typically you use a 5×5 for an RGBA image
and a 6×6 for CMYKA. Populate the last row with
normalized values to translate.</span></p>
<h4>Arguments</h4>
<p>An array of Float values representing the recolor
matrix.</p>
<h4>Magick API</h4>
<p>RecolorImage</p>
</div>
<div class="sig">
<h3 id="reduce_noise">reduce_noise</h3>
<p><span class="arg">img</span>.reduce_noise(<span class=
"arg">radius</span>) -> <em>image</em></p>
</div>
<div class="desc">
<h4>Description</h4>
<p class="imquote">Smooths the contours of an image while still
preserving edge information. The algorithm works by replacing
each pixel with its neighbor closest in value.</p>
<h4>Arguments</h4>
<dl>
<dt>radius</dt>
<dd class="imquote">A neighbor is defined by radius. Use a
radius of 0 and <code>reduce_noise</code> selects a suitable
radius for you.</dd>
</dl>
<h4>Returns</h4>
<p>A new image</p>
<h4>Example</h4>
<p>The left side of the image has been modified by <a href=
"#Image.add_noise"><code>add_noise</code></a>. The right side
has been filtered by <code>reduce_noise(0)</code>.</p>
<p><a href="javascript:popup('reduce_noise.rb.html')"><img src=
"ex/reduce_noise.jpg" title="Click to see the example script"
alt="reduce_noise example" /></a></p>
<h4>See also</h4>
<p><a href="image2.html#enhance">enhance</a>, <a href=
"#unsharp_mask">unsharp_mask</a></p>
<h4>Magick API</h4>
<p>ReduceNoiseImage</p>
</div>
<div class="sig">
<h3 id="resample">resample</h3>
<p><span class="arg">img</span>.resample(<span class=
"arg">horizontal_res</span>=72.0[, <span class=
"arg">vertical_res</span>]) -> <em>image</em></p>
</div>
<div class="desc">
<h4>Description</h4>
<p class="imquote">Resample image to specified horizontal and
vertical resolution.</p>
<p><span class="imquote">Resize the image so that its rendered
size remains the same as the original at the specified target
resolution. For example, if a 300 DPI image renders at 3 inches
by 2 inches on a 300 DPI device, when the image has been
resampled to 72 DPI, it will render at 3 inches by 2 inches on
a 72 DPI device. Note that only a small number of image formats
(e.g. JPEG, PNG, and TIFF) are capable of storing the image
resolution. For formats which do not support an image
resolution, the original resolution of the image must be
specified via</span> the <a href=
"imageattrs.html#density">density</a> attribute <span class=
"imquote">prior to specifying the resample
resolution.</span></p>
<h4>Arguments</h4>
<dl>
<dt>horizontal_res</dt>
<dd>the target horizontal resolution. The default is
72.0.</dd>
<dt>vertical_res</dt>
<dd>the target vertical resolution. The default is
<span class="arg">horizontal_res</span>.</dd>
</dl>
</div>
<div class="sig">
<h3 id="resize">resize</h3>
<p><span class="arg">img</span>.resize(<span class=
"arg">new_width</span>, <span class="arg">new_height</span>,
<em>filter</em>=<a href=
"constants.html#FilterTypes">LanczosFilter</a>,
<em>support</em>=1.0) -> <em>image</em><br />
<span class="arg">img</span>.resize(<span class=
"arg">scale_factor</span>) -> <em>image</em></p>
</div>
<div class="desc">
<h4>Description</h4>
<p>Changes the size of the receiver to the specified
dimensions.</p>
<h4>Arguments</h4>
<p>You can specify the new size in two ways. Either specify the
new width and height explicitly, or specify a <em>scale
factor</em>, a number that represents the percentage
change.</p>
<p>Use the <a href=
"image1.html#change_geometry">change_geometry</a> method to
resize an image with constraints such as "maintain the current
proportions."</p>
<dl>
<dt>new_width, new_height</dt>
<dd>The desired width and height.</dd>
<dt>filter</dt>
<dd>The <a href="constants.html#FilterTypes">filter</a> to
use when resizing. If you do not specify a filter argument,
resize uses the value of the receiver's <a href=
"imageattrs.html#Image.filter">filter attribute</a>.
<span class="imquote">Most of the filters are FIR (finite
impulse response), however, Bessel, Gaussian, and Sinc are
IIR (infinite impulse response). Bessel and Sinc are windowed
(brought down to zero) with the Blackman filter.</span></dd>
<dt>support</dt>
<dd>Values > 1 increase the blurriness. Values < 1
increase the sharpness. If this argument is not specified,
<code>resize</code> uses the value of the receiver's <a href=
"imageattrs.html#Image.blur">blur</a> attribute.</dd>
<dt>scale_factor</dt>
<dd>You can use this argument instead of specifying the
desired width and height. The percentage size change. For
example, 1.25 makes the new image 125% of the size of the
receiver. The scale factor 0.5 makes the new image 50% of the
size of the receiver.</dd>
</dl>
<h4>Returns</h4>
<p>A new image</p>
<h4>See also</h4>
<p><a href="image1.html#change_geometry">change_geometry</a>,
<a href="#resize_bang">resize!</a>, <a href=
"image2.html#magnify">magnify</a>, <a href=
"image2.html#minify">minify</a>, <a href="#sample">sample</a>,
<a href="#scale">scale</a>, <a href=
"thumbnail">thumbnail</a></p>
<h4>Magick API</h4>
<p>ResizeImage</p>
</div>
<div class="sig">
<h3 id="resize_bang">resize!</h3>
<p><span class="arg">img</span>.resize!(<em>new_width</em>,
<em>new_height</em>, <em>filter</em>=<a href=
"constants.html#FilterTypes">LanczosFilter</a>,
<em>support</em>=1.0) -> <em>self</em><br />
<span class="arg">img</span>.resize!(<span class=
"arg">scale_factor</span>) -> <em>self</em></p>
</div>
<div class="desc">
<h4>Description</h4>
<p>In-place form of <a href="#resize">resize</a>.</p>
<h4>Returns</h4>
<p>self</p>
</div>
<div class="sig">
<h3 id="resize_to_fill">resize_to_fill</h3>
<p><span class="arg">img</span>.resize_to_fill(<span class=
"arg">width</span> [, <span class="arg">height</span> [,
<span class="arg">gravity</span>=<code>CenterGravity</code>]])
-> <span class="arg">image</span></p>
</div>
<div class="desc">
<h4>Description</h4>
<p>A convenience method. Resize the image to fit within the
specified dimensions while retaining the aspect ratio of the
original image. If necessary, crop the image in the larger
dimension.</p>
<h4>Arguments</h4>
<dl>
<dt>width</dt>
<dd>The width of the resulting image in pixels</dd>
<dt>height</dt>
<dd>(Optional) The height of the resulting image in pixels.
If omitted, defaults to <span class="arg">width</span>.</dd>
<dt>gravity</dt>
<dd>Use this argument to specify which portion of the image
to retain when cropping. The value can be any <a href=
"constants.html#GravityType">GravityType</a> value. The
effect is the same as the <span class="arg">gravity</span>
argument to the <a href=
"image1.html#crop"><code>crop</code></a> method. The default
is <code>CenterGravity</code>.</dd>
</dl>
<h4>Returns</h4>
<p>A new image</p>
<h4>Example</h4>
<p>In this example, some rows have been cropped from the top
and bottom to produce a square thumbnail from a rectangular
image without distorting the image.</p>
<p class="rollover"><a href=
"javascript:popup('resize_to_fill.rb.html')">
<!-- This img tag displays the original image when the mouse is over -->
<img id="cropless" style="display: none" onmouseout=
"this.style.display='none';cropped.style.display='';" src=
"ex/images/Flower_Hat.jpg" alt="crop_resize example" title=
"Click to see the example script" />
<!-- This img tag displays the framed image when the mouse is not over-->
<img style=
"padding-left:62px; padding-right: 62px; padding-top: 87px;padding-bottom:87px;"
id="cropped" onmouseover=
"this.style.display='none';cropless.style.display='';" src=
"ex/resize_to_fill.jpg" alt="frame example" /></a> <img src=
"ex/images/spin.gif" alt="" style="margin-bottom: 230px" title=
"Mouse over the example to see the original image" /></p>
<h4>See also</h4>
<p><a href="image1.html#crop">crop</a>, <a href=
"#resize">resize</a>, <a href=
"#resize_to_fit">resize_to_fit</a></p>
<h4>Notes</h4>
<p><code>crop_resized</code> is an alias for this method.</p>
</div>
<div class="sig">
<h3 id="resize_to_fill_bang">resize_to_fill!</h3>
<p><span class="arg">img</span>.resize_to_fill!(<span class=
"arg">width</span> [, <span class="arg">height</span> [,
<span class="arg">gravity</span>=<code>CenterGravity</code>]])
-> <em>self</em></p>
</div>
<div class="desc">
<h4>Description</h4>The in-place form of <a href=
"#resize_to_fill">resize_to_fill</a>.
<h4>Returns</h4>
<p>self</p>
<h4>See also</h4>
<p><a href="image1.html#crop_bang">crop!</a>, <a href=
"#resize_bang">resize!</a>, <a href=
"#resize_to_fit_bang">resize_to_fit!</a></p>
<h4>Notes</h4>
<p><code>crop_resized!</code> is an alias for this method.</p>
</div>
<div class="sig">
<h3 id="resize_to_fit">resize_to_fit</h3>
<p><span class="arg">img</span>.resize_to_fit(<span class=
"arg">new_width</span> [, <span class="arg">new_height</span>])
-> <em>image</em></p>
</div>
<div class="desc">
<h4>Description</h4>
<p>A convenience method. Resize the image to fit within the
specified dimensions while retaining the original aspect ratio.
The image may be shorter or narrower than specified in the
smaller dimension but will not be larger than the specified
values.</p>
<h4>Arguments</h4>
<dl>
<dt>new_width</dt>
<dd>The maximum width of the resized image.</dd>
<dt>new_height</dt>
<dd>(Optional) The maximum height of the resized image. If
omitted it defaults to the value of <span class=
"arg">new_width</span>.</dd>
</dl>
<h4>Returns</h4>
<p>A new image</p>
<h4>Example</h4>
<p>Compare the result of this example to the result of the
<a href="#resize_to_fill">resize_to_fill</a> example above.</p>
<p class="rollover"><a href=
"javascript:popup('resize_to_fit.rb.html')">
<!-- This img tag displays the original image when the mouse is over -->
<img id="rtfless" style="display: none" onmouseout=
"this.style.display='none';rtf.style.display='';" src=
"ex/images/Flower_Hat.jpg" alt="resize_to_fill example" title=
"Click to see the example script" />
<!-- This img tag displays the framed image when the mouse is not over-->
<img style=
"padding-left:69px; padding-right: 69px; padding-top: 87px;padding-bottom:87px;"
id="rtf" onmouseover=
"this.style.display='none';rtfless.style.display='';" src=
"ex/resize_to_fit.jpg" alt="frame example" /></a> <img src=
"ex/images/spin.gif" alt="" style="margin-bottom: 230px" title=
"Mouse over the example to see the original image" /></p>
<h4>See also</h4>
<p><a href="#resize">resize</a>, <a href=
"#resize_to_fill">resize_to_fill</a></p>
</div>
<div class="sig">
<h3 id="resize_to_fit_bang">resize_to_fit!</h3>
<p><span class="arg">img</span>.resize_to_fit!(<span class=
"arg">new_width</span> [, <span class="arg">new_height</span>])
-> <em>self</em></p>
</div>
<div class="desc">
<h4>Description</h4>
<p>In-place form of <a href=
"#resize_to_fit">resize_to_fit</a>.</p>
<h4>Returns</h4>
<p>self</p>
<h4>See also</h4>
<p><a href="#resize_bang">resize!</a>, <a href=
"#resize_to_fill_bang">resize_to_fill!</a></p>
</div>
<div class="sig">
<h3 id="roll">roll</h3>
<p><span class="arg">img</span>.roll(<span class=
"arg">x_offset</span>, <span class="arg">y_offset</span>) ->
<em>image</em></p>
</div>
<div class="desc">
<h4>Description</h4>
<p class="imquote">Offsets an image as defined by <span class=
"arg">x_offset</span> and <span class=
"arg">y_offset</span>.</p>
<h4>Arguments</h4>
<dl>
<dt>x_offset</dt>
<dd>The number of columns to offset the image.</dd>
<dt>y_offset</dt>
<dd>The number of rows to offset the image.</dd>
</dl>
<h4>Returns</h4>
<p>A new image</p>
<h4>Example</h4>
<p>This image has been offset 25% in both directions.</p>
<p class="rollover"><a href=
"javascript:popup('roll.rb.html')"><img src="ex/roll.jpg"
title="Click to see the example script" alt="roll example"
onmouseover="this.src='ex/images/Flower_Hat.jpg'" onmouseout=
"this.src='ex/roll.jpg'" /></a><img src="ex/images/spin.gif"
alt="" class="spin" title=
"Mouse over the example to see the original image" /></p>
<h4>Magick API</h4>
<p>RollImage</p>
</div>
<div class="sig">
<h3 id="rotate">rotate</h3>
<p><span class="arg">img</span>.rotate(<span class=
"arg">amount</span> [, <span class="arg">qualifier</span>])
-> <em>image</em></p>
</div>
<div class="desc">
<h4>Description</h4>
<p>Rotate the receiver by the specified angle. Positive angles
rotate clockwise while negative angles rotate
counter-clockwise. New pixels introduced by the rotation are
the same color as the current <a href=
"imageattrs.html#background_color">background color</a>. Set
the background color to "none" to make the new pixels
transparent black.</p>
<h4>Arguments</h4>
<dl>
<dt>amount</dt>
<dd>The number of degrees to rotate the image.</dd>
<dt>qualifier</dt>
<dd>If present, either ">" or "<". If ">", rotates
the image only if the image's width exceeds its height. If
"<" rotates the image only if its height exceeds its
width. If this argument is omitted the image is always
rotated.</dd>
</dl>
<h4>Returns</h4>
<p>A new image, or <code>nil</code> if the image was not
rotated because it did not meet the qualification specified by
the second argument.</p>
<h4>Example</h4>
<p class="rollover"><a href=
"javascript:popup('rotate_f.rb.html')"><!--
This img tag displays the original image when the mouse is over.
Use CSS to add padding around the image to make it occupy the
same space as the rotated image. --><img style="padding-top:34px;padding-bottom:34px; display:none"
id="notrotated" onmouseout=
"this.style.display='none'; rotated.style.display='';" src=
"ex/images/Flower_Hat.jpg" alt="rotate example" title=
"Click to see the example script" /><!--
This img tag displays the rotated image.
--><img class="hide"
id="rotated" onmouseover=
"this.style.display='none'; notrotated.style.display='';" src=
"ex/rotate_f.jpg" alt="rotate example" /></a> <img src=
"ex/images/spin.gif" alt="" class="spin" style="left:322px;"
title="Mouse over the example to see the original image" /></p>
<h4>See also</h4>
<p><a href="image1.html#affine_transform">affine_transform</a>,
<a href="#shear">shear</a></p>
<h4>Magick API</h4>
<p>RotateImage</p>
</div>
<div class="sig">
<h3 id="rotate_bang">rotate!</h3>
<p><span class="arg">img</span>.rotate!(<span class=
"arg">amount</span> [, <span class="arg">qualifier</span>])
-> <em>self</em></p>
</div>
<div class="desc">
<h4>Description</h4>
<p>In-place form of <a href="#rotate">rotate</a>.</p>
<h4>Returns</h4>
<p>self, or <code>nil</code> if the image was not rotated
because it did not meet the qualification specified by the
second argument.</p>
</div>
<div class="sig">
<h3 id="sample">sample</h3>
<p><span class="arg">img</span>.sample(<span class=
"arg">new_width</span>, <span class="arg">new_height</span>)
-> <span class="arg">image</span><br />
<span class="arg">img</span>.sample(<span class=
"arg">scale_factor</span>) -> <em>image</em></p>
</div>
<div class="desc">
<h4>Description</h4>
<p>Scales an image to the desired dimensions with pixel
sampling. Unlike other scaling methods, this method does not
introduce any additional color into the scaled image.</p>
<h4>Arguments</h4>
<dl>
<dt>new_width, new_height</dt>
<dd>The desired width and height.</dd>
<dt>scale_factor</dt>
<dd>You can use this argument instead of specifying the
desired width and height. The percentage size change. For
example, 1.25 makes the new image 125% of the size of the
receiver. The scale factor 0.5 makes the new image 50% of the
size of the receiver.</dd>
</dl>
<h4>Returns</h4>
<p>A new image</p>
<h4>See also</h4>
<p><a href="#sample_bang">sample!</a>, <a href=
"image2.html#magnify">magnify</a>, <a href=
"image2.html#minify">minify</a>, <a href="#resize">resize</a>,
<a href="#scale">scale</a>, <a href=
"#thumbnail">thumbnail</a></p>
<h4>Magick API</h4>
<p>SampleImage</p>
</div>
<div class="sig">
<h3 id="sample_bang">sample!</h3>
<p><span class="arg">img</span>.sample!(<span class=
"arg">new_width</span>, <span class="arg">new_height</span>)
-> <em>self</em><br />
<span class="arg">img</span>.sample!(<span class=
"arg">scale_factor</span>) -> <em>self</em></p>
</div>
<div class="desc">
<h4>Description</h4>
<p>In-place form of <a href="#sample">sample</a>.</p>
<h4>Returns</h4>
<p>self</p>
</div>
<div class="sig">
<h3 id="scale">scale</h3>
<p><span class="arg">img</span>.scale(<span class=
"arg">new_width</span>, <span class="arg">new_height</span>)
-> <em>image</em><br />
<span class="arg">img</span>.scale(<span class=
"arg">scale_factor</span>) -> <em>image</em></p>
</div>
<div class="desc">
<h4>Description</h4>
<p class="imquote">Changes the size of an image to the given
dimensions.</p>
<h4>Arguments</h4>
<dl>
<dt>new_width, new_height</dt>
<dd>The desired width and height.</dd>
<dt>scale_factor</dt>
<dd>You can use this argument instead of specifying the
desired width and height. The percentage size change. For
example, 1.25 makes the new image 125% of the size of the
receiver. The scale factor 0.5 makes the new image 50% of the
size of the receiver.</dd>
</dl>
<h4>Returns</h4>
<p>A new image</p>
<h4>See also</h4>
<p><a href="#scale_bang">scale!</a>, <a href=
"image2.html#magnify">magnify</a>, <a href=
"image2.html#minify">minify</a>, <a href="#resize">resize</a>,
<a href="#sample">sample</a>, <a href=
"#thumbnail">thumbnail</a></p>
<h4>Magick API</h4>
<p>ScaleImage</p>
</div>
<div class="sig">
<h3 id="scale_bang">scale!</h3>
<p><span class="arg">img</span>.scale!(<span class=
"arg">new_width</span>, <span class="arg">new_height</span>)
-> <em>self</em><br />
<span class="arg">img</span>.scale!(<span class=
"arg">scale_factor</span>) -> <em>self</em></p>
</div>
<div class="desc">
<h4>Description</h4>
<p>In-place form of <a href="#scale">scale</a>.</p>
<h4>Returns</h4>
<p>self</p>
</div>
<div class="sig">
<h3 id="segment">segment</h3>
<p><span class="arg">img</span>.segment(<span class=
"arg">colorspace</span>=RGBColorspace, <span class=
"arg">cluster_threshold</span>=1.0, <span class=
"arg">smoothing_threshold</span>=1.5, <span class=
"arg">verbose</span>=<code>false</code>) ->
<em>image</em></p>
</div>
<div class="desc">
<h4>Description</h4>
<p class="imquote">Segments an image by analyzing the
histograms of the color components and identifying units that
are homogeneous with the fuzzy c-means technique.</p>
<h4>Arguments</h4>
<dl>
<dt>colorspace</dt>
<dd>A <a href=
"constants.html#ColorspaceType"><code>ColorspaceType</code></a>
value. <span class="imquote">Empirical evidence suggests that
distances in YUV or YIQ correspond to perceptual color
differences more closely than do distances in RGB space. The
image is then returned to RGB colorspace after color
reduction.</span></dd>
<dt>cluster_threshold</dt>
<dd class="imquote">The number of pixels in each cluster must
exceed the the cluster threshold to be considered valid.</dd>
<dt>smoothing_threshold</dt>
<dd>The <span class="imquote">smoothing threshold eliminates
noise in the second derivative of the histogram. As the value
is increased, you can expect a smoother second
derivative.</span></dd>
<dt>verbose</dt>
<dd>If <code>true</code>, <code>segment</code> prints
detailed information about the identified classes.</dd>
</dl>
<h4>Returns</h4>
<p>A new image</p>
<h4>Example</h4>
<p><code>segment(YUVColorspace, 0.4, 0.4)</code></p>
<p class="rollover"><a href=
"javascript:popup('segment.rb.html')"><img src="ex/segment.jpg"
alt="segment example" title="Click to see the example script"
onmouseover="this.src='ex/images/Flower_Hat.jpg'" onmouseout=
"this.src='ex/segment.jpg'" /></a> <img src=
"ex/images/spin.gif" alt="" class="spin" title=
"Mouse over the example to see the original image" /></p>
<h4>Magick API</h4>
<p>SegmentImage</p>
</div>
<div class="sig">
<h3 id="separate">separate</h3>
<p>Image.separate(<span class="arg">channel</span>...) ->
<span class="arg">imagelist</span></p>
</div>
<div class="desc">
<h4>Description</h4>
<p>Constructs a grayscale image for each channel specified.</p>
<h4>Arguments</h4>
<p>0 or more <a href=
"constants.html#ChannelType">ChannelType</a> arguments. If no
channels are specified, constructs an image for each of the
red, green, and blue channels.</p>
<h4>Returns</h4>
<p>A new imagelist containing the new images.</p>
<h4>See also</h4>
<p><a href="image1.html#channel">channel</a></p>
<h4>Notes</h4>
<p>If the image does not have an opacity channel an
OpacityChannel argument is ignored.</p>
<h4>Magick API</h4>
<p>SeparateImages</p>
</div>
<div class="sig">
<h3 id="sepiatone">sepiatone</h3>
<p><span class="arg">img</span>.sepiatone(<span class=
"arg">threshold</span>=QuantumRange) -> <span class=
"arg">image</span></p>
</div>
<div class="desc">
<h4>Description</h4>
<p class="imquote">Applies a special effect to the image,
similar to the effect achieved in a photo darkroom by sepia
toning.</p>
<h4>Arguments</h4>
<dl>
<dt>threshold</dt>
<dd class="imquote"><span class="arg">Threshold</span> ranges
from 0 to QuantumRange and is a measure of the extent of the
sepia toning. A threshold of 80% is a good starting point for
a reasonable tone. The default is QuantumRange.</dd>
</dl>
<h4>Returns</h4>
<p>A new image.</p>
<h4>Example</h4>
<p class="rollover"><a href=
"javascript:popup('sepiatone.rb.html')"><img src=
"ex/sepiatone.jpg" alt="sepiatone example" onmouseover=
"this.src='ex/images/Flower_Hat.jpg'" onmouseout=
"this.src='ex/sepiatone.jpg'" title=
"Click to see the example script" /></a> <img src=
"ex/images/spin.gif" alt="" class="spin" title=
"Mouse over the example to see the original image" /></p>
<h4>See also</h4>
<p>You can get more control by using <a href=
"image1.html#colorize">colorize</a>.</p>
<h4>Magick API</h4>
<p>SepiaToneImage</p>
</div>
<div class="sig">
<h3 id="set_channel_depth">set_channel_depth</h3>
<p><span class="arg">img.</span>set_channel_depth(<span class=
"arg">channel</span>, <span class="arg">depth</span>) ->
<em>self</em></p>
</div>
<div class="desc">
<h4>Description</h4>
<p>Sets the depth of the image channel.</p>
<h4>Arguments</h4>
<dl>
<dt>channel</dt>
<dd>A <a href="constants.html#ChannelType">ChannelType</a>
value</dd>
<dt>depth</dt>
<dd>The desired depth (must be no greater than <a href=
"constants.html">QuantumDepth</a>)</dd>
</dl>
<h4>Returns</h4>
<p>self</p>
<h4>See also</h4>
<p><a href="image1.html#channel_depth">channel_depth</a></p>
<h4>Magick API</h4>
<p>SetImageChannelDepth</p>
</div>
<div class="sig">
<h3 id="shade">shade</h3>
<p><span class="arg">img</span>.shade(<span class=
"arg">shading</span>=<code>false</code>, <span class=
"arg">azimuth</span>=30, <span class="arg">elevation</span>=30)
-> <em>image</em></p>
</div>
<div class="desc">
<h4>Description</h4>
<p class="imquote">Shines a distant light on an image to create
a three-dimensional effect. You control the positioning of the
light with <span class="arg">azimuth</span> and <span class=
"arg">elevation</span>; <span class="arg">azimuth</span> is
measured in degrees off the x axis and <span class=
"arg">elevation</span> is measured in pixels above the Z
axis.</p>
<h4>Arguments</h4>
<dl>
<dt>shading</dt>
<dd>If <code>true</code>, <code>shade</code> shades the
intensity of each pixel.</dd>
<dt>azimuth, elevation</dt>
<dd>The light source direction. The azimuth is measured in
degrees. 0° is at 9 o'clock. Increasing values move the
light source counter-clockwise.</dd>
</dl>
<h4>Returns</h4>
<p>A new image</p>
<h4>Example</h4>
<p><code>shade(true, 50, 50)</code></p>
<p class="rollover"><a href=
"javascript:popup('shade.rb.html')"><img src="ex/shade.jpg"
alt="shade example" onmouseover=
"this.src='ex/images/Flower_Hat.jpg'" onmouseout=
"this.src='ex/shade.jpg'" title=
"Click to see the example script" /></a> <img src=
"ex/images/spin.gif" alt="" class="spin" title=
"Mouse over the example to see the original image" /></p>
<h4>Magick API</h4>
<p>ShadeImage</p>
</div>
<div class="sig">
<h3 id="shadow">shadow</h3>
<p><span class="arg">img</span>.shadow(<span class=
"arg">x_offset=4</span>, <span class="arg">y_offset=4</span>,
<span class="arg">sigma=4.0</span>, <span class=
"arg">opacity=1.0</span>) -> <em>image</em></p>
</div>
<div class="desc">
<h4>Description</h4>Draws the shadow of opaque parts of the
image. This method only works when the image has opaque parts
and transparent parts. Note that the resulting image is just
the shadow. You must composite the original image over the
shadow to produce the shadowed results.
<h4>Arguments</h4>
<dl>
<dt>x_offset</dt>
<dd>The shadow x-offset</dd>
<dt>y_offset</dt>
<dd>The shadow y-offset</dd>
<dt>sigma</dt>
<dd>The standard deviation of the Gaussian operator used to
produce the shadow. The higher the number, the "blurrier" the
shadow, but the longer it takes to produce the shadow. Must
be > 0.0.</dd>
<dt>opacity</dt>
<dd>The percent opacity of the shadow. May be either a number
between 0.1 and 1.0, or a string in the form "NN%" between
"1%" and "100%". If the percentage is greater than 100 it is
reduced to 100.</dd>
</dl>
<h4>Returns</h4>
<p>A new image</p>
<h4>Example</h4>
<p class="rollover"><a href=
"javascript:popup('shadow.rb.html')">
<!-- This img tag displays the original image when the mouse is over -->
<img style="padding:8px; display:none" id="shadowless"
onmouseout=
"this.style.display='none';shadowed.style.display='';" src=
"ex/shadow_before.gif" alt="shadow example" title=
"Click to see the example script" /><!--
This img tag displays the shadowed image when the mouse is not over
--><img class="hide"
id="shadowed" onmouseover=
"this.style.display='none';shadowless.style.display='';" src=
"ex/shadow_after.gif" alt="shadow example" /></a> <img src=
"ex/images/spin.gif" alt="" style="margin-bottom: 120px" title=
"Mouse over the example to see the original image" /></p>
<h4>Magick API</h4>
<p>ShadowImage</p>
<h4>Notes</h4>
<p>The shadow image is 2×<span class="arg">sigma</span>
pixels larger on a side than the original image, as can be seen
in the example above.</p>
</div>
<div class="sig">
<h3 id="sharpen">sharpen</h3>
<p><span class="arg">img</span>.sharpen(<span class=
"arg">radius</span>=0.0, <span class="arg">sigma</span>=1.0)
-> <em>image</em></p>
</div>
<div class="desc">
<h4>Description</h4>
<p class="imquote">Sharpens an image. We convolve the image
with a Gaussian operator of the given <span class=
"arg">radius</span> and standard deviation (<span class=
"arg">sigma</span>). For reasonable results, <span class=
"arg">radius</span> should be larger than <span class=
"arg">sigma</span>. Use a radius of 0 and <code>sharpen</code>
selects a suitable radius for you.</p>
<h4>Arguments</h4>
<p>The radius and standard deviation of the Gaussian
operator.</p>
<h4>Returns</h4>
<p>A new image</p>
<h4>Magick API</h4>
<p>SharpenImage</p>
<h4>See also</h4>
<p><a href=
"imageattrs.html#virtual_pixel_method">virtual_pixel_method</a></p>
</div>
<div class="sig">
<h3 id="sharpen_channel">sharpen_channel</h3>
<p><span class="arg">img</span>.sharpen_channel( <span class=
"arg">radius</span>, <span class="arg">sigma</span>
[,<span class="arg">channel</span>...] ) ->
<em>image</em></p>
</div>
<div class="desc">
<h4>Description</h4>
<p class="imquote">Sharpens one or more image channels. We
convolve the image with a Gaussian operator of the given radius
and standard deviation (<span class="arg">sigma</span>) . For
reasonable results, <span class="arg">radius</span> should be
larger than <span class="arg">sigma</span>. Use a radius of 0
and <code>sharpen_channel</code> selects a suitable radius for
you.</p>
<h4>Arguments</h4>
<dl>
<dt>radius, sigma</dt>
<dd>The radius and standard deviation of the Gaussian
operator.</dd>
<dt>channel...</dt>
<dd>0 or more <a href=
"constants.html#ChannelType">ChannelType</a> arguments. If no
channels are specified, all the channels are sharpened.</dd>
</dl>
<h4>Returns</h4>
<p>A new image</p>
<h4>See also</h4>
<p><a href="#sharpen">sharpen</a></p>
<h4>Magick API</h4>
<p>SharpenImageChannel</p>
</div>
<div class="sig">
<h3 id="shave">shave</h3>
<p><span class="arg">img</span>.shave(<span class=
"arg">width</span>, <span class="arg">height</span>) ->
<em>image</em></p>
</div>
<div class="desc">
<h4>Description</h4>
<p>Removes pixels from the edges of the image, leaving the
center rectangle.</p>
<h4>Arguments</h4>
<dl>
<dt>width</dt>
<dd>The number of pixels to remove from each side of the
receiver, not to exceed half the original width.</dd>
<dt>height</dt>
<dd>The number of pixels to remove from the top and bottom of
the receiver, not to exceed half the original height.</dd>
</dl>
<h4>Returns</h4>
<p>A new image</p>
<h4>Example</h4>
<p class="rollover"><a href=
"javascript:popup('shave.rb.html')"><img src="ex/shave.jpg"
onmouseover="this.src='ex/images/Flower_Hat.jpg'" onmouseout=
"this.src='ex/shave.jpg'" alt="shave example" title=
"Click to see the example script" /></a> <img src=
"ex/images/spin.gif" alt="" class="spin" title=
"Mouse over the example to see the original image" /></p>
<h4>See also</h4>
<p><a href="#shave_bang">shave!</a>, <a href=
"image1.html#crop">crop</a></p>
<h4>Magick API</h4>
<p>ShaveImage</p>
</div>
<div class="sig">
<h3 id="shave_bang">shave!</h3>
<p><span class="arg">img</span>.shave!(<span class=
"arg">width</span>, <span class="arg">height</span>) ->
<em>self</em></p>
</div>
<div class="desc">
<h4>Description</h4>
<p>In-place form of <a href="#shave">shave</a>.</p>
<h4>Returns</h4>
<p>self</p>
</div>
<div class="sig">
<h3 id="shear">shear</h3>
<p><span class="arg">img</span>.shear(<span class=
"arg">x_shear</span>, <span class="arg">y_shear</span>) ->
<em>image</em></p>
</div>
<div class="desc">
<h4>Description</h4>
<p class="imquote">Shearing slides one edge of an image along
the X or Y axis, creating a parallelogram. An X direction shear
slides an edge along the X axis, while a Y direction shear
slides an edge along the Y axis. The amount of the shear is
controlled by a shear angle. For X direction shears,
<span class="arg">x_shear</span> is measured relative to the Y
axis, and similarly, for Y direction shears <span class=
"arg">y_shear</span> is measured relative to the X axis. Empty
triangles left over from shearing the image are filled with the
background color.</p>
<h4>Arguments</h4>
<p>The X and Y shear angles, measured in degrees. These values
must not be 180.0. If either value is 0, no shearing will
occur.</p>
<h4>Returns</h4>
<p>A new image</p>
<h4>Example</h4>
<p class="rollover"><a href=
"javascript:popup('shear.rb.html')"><!--
This img tag displays the original image when the mouse is over
--><img style="padding-top:34px; padding-bottom:33px; padding-left:49px; padding-right:49px; display:none"
id="noshear" onmouseout=
"this.style.display='none'; sheared.style.display='';" src=
"ex/images/Flower_Hat.jpg" alt="shear example" title=
"Click to see the example script" /> <!--
This img tag displays the sheared image when the mouse is not over
-->
<img id="sheared" onmouseover=
"this.style.display='none'; noshear.style.display='';" src=
"ex/shear.jpg" alt="shear example" /></a><img src=
"ex/images/spin.gif" alt="" class="spin" style=
"left: 253px; top: 34px" title=
"Mouse over the example to see the original image" /></p>
<h4>See also</h4>
<p><a href="image1.html#affine_transform">affine_transform</a>,
<a href="#rotate">rotate</a></p>
<h4>Magick API</h4>
<p>ShearImage</p>
</div>
<div class="sig">
<h3 id="sigmoidal_contrast_channel">
sigmoidal_contrast_channel</h3>
<p><br />
<span class=
"arg">img</span>.sigmoidal_contrast_channel(<span class=
"arg">contrast</span>=3.0, <span class=
"arg">midpoint</span>=50.0, <span class=
"arg">sharpen</span>=false[,<span class=
"arg">channel</span>...]) -> <em>image</em></p>
</div>
<div class="desc">
<h4>Description</h4>
<p class="imquote">Adjusts the contrast of an image channel
with a non-linear sigmoidal contrast algorithm. Increases the
contrast of the image using a sigmoidal transfer function
without saturating highlights or shadows.</p>
<h4>Arguments</h4>
<dl>
<dt>contrast</dt>
<dd class="imquote">indicates how much to increase the
contrast (0 is none; 3 is typical; 20 is pushing it)</dd>
<dt>midpoint</dt>
<dd class="imquote">indicates where midtones fall in the
resultant image (0 is white; 50% is middle-gray; 100% is
black)</dd>
<dt>sharpen</dt>
<dd class="imquote">Set <span class="arg">sharpen</span> to
<code>true</code> to increase the image contrast otherwise
the contrast is reduced.</dd>
<dt>channel...</dt>
<dd>0 or more <a href=
"constants.html#ChannelType">ChannelType</a> arguments. If no
channels are specified, all the channels are adjusted.</dd>
</dl>
<h4>Returns</h4>
<p>A new image</p>
<h4>See also</h4>
<p><a href="image1.html#contrast">contrast</a></p>
<h4>Magick API</h4>
<p>SigmoidalContrastImageChannel</p>
</div>
<div class="sig">
<h3 id="signature">signature</h3>
<p><span class="arg">img</span>.signature ->
<em>string</em></p>
</div>
<div class="desc">
<h4>Description</h4>
<p class="imquote">Computes a message digest from an image
pixel stream with an implementation of the NIST SHA-256 Message
Digest algorithm. This signature uniquely identifies the image
and is convenient for determining if an image has been modified
or whether two images are identical.</p>
<p>ImageMagick adds the computed signature to the image's
properties.</p>
<h4>Returns</h4>
<p>The signature as a 64-character string.</p>
<h4>Example</h4>
<pre>
img = Image.read('ex/images/Flower_Hat.jpg').first »
ex/images/Flower_Hat.jpg JPEG 200x250 DirectClass 8-bit 9761b
img.properties »
{"comment"=>"File written by Adobe Photoshop\250 4.0"}
img.signature »
"485e01ecba1a1f47924d67b887cb07b474f695841733796dfa3c2876965c7e8b"
img.properties »
{"signature"=>"485e01ecba1a1f47924d67b887cb07b474f695841733796dfa3c2876965c7e8b",
"comment"=>"File written by Adobe Photoshop\250 4.0"}
</pre>
<h4>See also</h4>
<p><a href="image1.html#spaceship"><=></a>, <a href=
"image1.html#difference">difference</a></p>
<h4>Magick API</h4>
<p>SignatureImage</p>
</div>
<div class="sig">
<h3 id="sketch">sketch</h3>
<p><span class="arg">img</span>.sketch(<span class=
"arg">radius</span>=0.0, <span class="arg">sigma</span>=1.0,
<span class="arg">angle</span>=0.0) -> <em>image</em></p>
</div>
<div class="desc">
<h4>Description</h4>
<p>Simulates a pencil sketch. For best results start with a
grayscale image.</p>
<h4>Arguments</h4>
<dl>
<dt>radius, sigma</dt>
<dd>The radius and sigma of the Gaussian operator</dd>
<dt>angle</dt>
<dd>The angle toward which the image is sketched.</dd>
</dl>
<h4>Returns</h4>
<p>A new image</p>
<h4>Example</h4>
<p class="rollover"><a href=
"javascript:popup('sketch.rb.html')"><img src="ex/sketch.jpg"
title="Click to see the example script" alt="sketch example"
onmouseover="this.src='ex/images/Flower_Hat.jpg'" onmouseout=
"this.src='ex/sketch.jpg'" /></a> <img src="ex/images/spin.gif"
alt="" class="spin" title=
"Mouse over the example to see the original image" /></p>
<h4>Magick API</h4>
<p>SketchImage</p>
</div>
<div class="sig">
<h3 id="solarize">solarize</h3>
<p><span class="arg">img</span>.solarize(<span class=
"arg">threshold</span>=50) -> <em>image</em></p>
</div>
<div class="desc">
<h4>Description</h4>
<p class="imquote">Applies a special effect to the image
similar to the effect achieved in a photo darkroom by
selectively exposing areas of photo sensitive paper to
light.</p>
<h4>Arguments</h4>
<p><span class="imquote">Ranges from 0 to QuantumRange and is a
measure of the extent of the solarization.</span> The default
is 50.</p>
<h4>Returns</h4>
<p>A new image</p>
<h4>Example</h4>
<p class="rollover"><a href=
"javascript:popup('solarize.rb.html')"><img src=
"ex/solarize.jpg" title="Click to see the example script" alt=
"solarize example" onmouseover=
"this.src='ex/images/Flower_Hat.jpg'" onmouseout=
"this.src='ex/solarize.jpg'" /></a> <img src=
"ex/images/spin.gif" alt="" class="spin" title=
"Mouse over the example to see the original image" /></p>
<h4>Magick API</h4>
<p>SolarizeImage</p>
</div>
<div class="sig">
<h3 id="splice">splice</h3>
<p><span class="arg">img</span>.splice(<span class=
"arg">x</span>, <span class="arg">y</span>, <span class=
"arg">width</span>, <span class="arg">height</span>[,
<span class="arg">color</span>]) -> <em>image</em></p>
</div>
<div class="desc">
<h4>Description</h4>
<p>Splice a solid color into the image as defined by the
<code>x</code>, <code>y</code>, <code>width</code>, and
<code>height</code> arguments. This method is the opposite of
<a href="image1.html#chop">chop</a>.</p>
<h4>Arguments</h4>
<dl>
<dt>x, y, width, height</dt>
<dd>Describe the rectangle to be spliced.</dd>
<dt>color</dt>
<dd>The color to be spliced. Either a <a href=
"imusage.html#color_names">color name</a> or a <a href=
"struct.html#Pixel">pixel</a>. If omitted, uses the image's
background color.</dd>
</dl>
<h4>Returns</h4>
<p>A new image</p>
<h4>Example</h4>
<p class="rollover"><a href=
"javascript:popup('splice.rb.html')">
<!-- This img tag displays the original image when the mouse is over -->
<img style=
"padding-left:8px;padding-right:8px;padding-bottom:10px;padding-bottom:10px; display:none"
id="nosplice" onmouseout=
"this.style.display='none';spliced.style.display='';" src=
"ex/images/Flower_Hat.jpg" alt="splice example" title=
"Click to see the example script" /><!--
This img tag displays the spliced image when the mouse is not over
--><img class="hide"
id="spliced" onmouseover=
"this.style.display='none';nosplice.style.display='';" src=
"ex/splice.jpg" alt="splice example" /></a> <img src=
"ex/images/spin.gif" alt="" style="margin-bottom: 280px" title=
"Mouse over the example to see the original image" /></p>
<h4>See also</h4>
<p><a href=
"image1.html#color_fill_to_border">color_fill_to_border</a>,
<a href="image1.html#color_floodfill">color_floodfill</a>,
<a href="image1.html#color_reset_bang">color_reset!</a>,
<a href="image2.html#erase_bang">erase!</a>, <a href=
"image2.html#opaque">opaque</a></p>
<h4>Magick API</h4>
<p>SpliceImage</p>
</div>
<div class="sig">
<h3 id="spread">spread</h3>
<p><span class="arg">img</span>.spread(<span class=
"arg">radius</span>=3) -> <em>image</em></p>
</div>
<div class="desc">
<h4>Description</h4>
<p class="imquote">Randomly displaces each pixel in a block
defined by the <span class="arg"><em>radius</em></span>
parameter.</p>
<h4>Returns</h4>
<p>A new image</p>
<h4>Example</h4>
<p class="rollover"><a href=
"javascript:popup('spread.rb.html')"><img src="ex/spread.jpg"
alt="spread example" title="Click to see the example script"
onmouseover="this.src='ex/images/Flower_Hat.jpg'" onmouseout=
"this.src='ex/spread.jpg'" /></a> <img src="ex/images/spin.gif"
alt="" class="spin" title=
"Mouse over the example to see the original image" /></p>
<h4>Magick API</h4>
<p>SpreadImage</p>
</div>
<div class="sig">
<h3 id="stegano">stegano</h3>
<p><span class="arg">img</span>.stegano(<span class=
"arg">watermark</span>, <span class="arg">offset</span>) ->
<em>image</em></p>
</div>
<div class="desc">
<h4>Description</h4>
<p>Hides a digital watermark in the receiver. You can retrieve
the watermark by reading the file with the
<code>stegano:</code> prefix, thereby proving the authenticity
of the file.</p>
<p>The watermarked image must be saved in a lossless RGB format
such as MIFF, or PNG. You cannot save a watermarked image in a
lossy format such as JPEG or a pseudocolor format such as GIF.
Once written, the file must not be modified or processed in any
way.</p>
<h4>Arguments</h4>
<dl>
<dt>watermark</dt>
<dd>An image or imagelist to be used as the watermark. The
watermark must be grayscale and should be substantially
smaller than the receiver. The recovery time is proportional
to the size of the watermark.</dd>
<dt>offset</dt>
<dd>The starting position within the receiver at which the
watermark will be hidden. When you retrieve the watermark
from the file, you must supply this value, along with the
width and height of the watermark, in the <a href=
"info.html#Info.size_eq">size</a> optional parameter to the
<a href="image1.html#read">read</a> method.</dd>
</dl>
<h4>Returns</h4>
<p>A copy of the image containing the embedded watermark.</p>
<h4>Example</h4>
<p><a href="javascript:popup('stegano.rb.html')"><img src=
"ex/stegano.gif" title="Click to see the example script" alt=
"stegano example" /></a></p>
<h4>Magick API</h4>
<p>SteganoImage</p>
<h4>See also</h4>
<p><a href="#watermark">watermark</a></p>
</div>
<div class="sig">
<h3 id="stereo">stereo</h3>
<p><span class="arg">img</span>.stereo(<span class=
"arg">offset_image</span>) -> <em>image</em></p>
</div>
<div class="desc">
<h4>Description</h4>
<p class="imquote">Combines two images and produces a single
image that is the composite of a left and right image of a
stereo pair. Special red-green stereo glasses are required to
view this effect.</p>
<h4>Arguments</h4>
<p>Another image or imagelist. If the argument is an imagelist,
uses the current image.</p>
<h4>Returns</h4>
<p>A new image</p>
<h4>Magick API</h4>
<p>StereoImage</p>
</div>
<div class="sig">
<h3 id="store_pixels">store_pixels</h3>
<p><span class="arg">img</span>.store_pixels(<span class=
"arg">x</span>, <span class="arg">y</span>, <span class=
"arg">columns</span>, <span class="arg">rows</span>,
<span class="arg">pixels</span>) -> <em>image</em></p>
</div>
<div class="desc">
<h4>Description</h4>
<p>Replace the pixels in the specified rectangle with the
pixels in the <em>pixels</em> array.</p>
<h4>Arguments</h4>
<dl>
<dt>x, y</dt>
<dd>The x- and y-offset of the rectangle to be replaced.</dd>
<dt>columns, rows</dt>
<dd>The number of rows and columns in the rectangle.</dd>
<dt>pixels</dt>
<dd>An array of <a href="struct.html#Pixel">pixels</a>. The
number of pixels in the array must be the same as the number
of pixels in the rectangle, that is,
<code>rows*columns</code>.</dd>
</dl>
<h4>Returns</h4>
<p>The image, with the rectangle suitably altered.</p>
<h4>Example</h4>
<p><a href="javascript:popup('smile.rb.html')"><img src=
"ex/smile.gif" title="Click to see the example script" alt=
"smile example" /></a></p>
<p>Also see the example for <a href=
"image2.html#get_pixels"><code>get_pixels</code></a>.</p>
<h4>See also</h4>
<p><a href="image1.html#constitute">constitute</a>, <a href=
"image2.html#get_pixels">get_pixels</a>, <a href=
"#view">view</a></p>
<h4>Magick API</h4>
<p>SetImagePixels, SyncImagePixels</p>
</div>
<div class="sig">
<h3 id="strip_bang">strip!</h3>
<p><span class="arg">img</span>.strip! -> <em>self</em></p>
</div>
<div class="desc">
<h4>Description</h4>
<p class="imquote">Strips an image of all profiles and
comments.</p>
<h4>Returns</h4>
<p>self</p>
<h4>Magick API</h4>
<p>StripImage</p>
</div>
<div class="sig">
<h3 id="swirl">swirl</h3>
<p><span class="arg">img</span>.swirl(<span class=
"arg">degrees</span>) -> <em>image</em></p>
</div>
<div class="desc">
<h4>Description</h4>
<p class="imquote">Swirls the pixels about the center of the
image, where degrees indicates the sweep of the arc through
which each pixel is moved. You get a more dramatic effect as
the degrees move from 1 to 360.</p>
<h4>Arguments</h4>
<p>The number of degrees to swirl the image.</p>
<h4>Returns</h4>
<p>A new image</p>
<h4>Example</h4>
<p>This example is an animated image. Mouse over the image to
start the animation.</p>
<p class="rollover"><a href=
"javascript:popup('swirl.rb.html')"><img onmouseover=
"this.src='ex/swirl.gif'" onmouseout=
"this.src='ex/images/Flower_Hat.jpg'" src=
"ex/images/Flower_Hat.jpg" alt="swirl example" title=
"Click the image to see the example script" /></a><img src=
"ex/images/spin.gif" alt="" class="spin" title=
"Mouse over the example to see the animation" /></p>
<h4>Magick API</h4>
<p>SwirlImage</p>
</div>
<div class="sig">
<h3 id="sync_profiles">sync_profiles</h3>
<p><span class="arg">img</span>.sync_profiles ->
<code>true</code> or <code>false</code></p>
</div>
<div class="desc">
<h4>Description</h4>
<p class="imquote">Synchronizes image properties with the image
profiles.</p>
<h4>Returns</h4>
<p><code>True</code> if everything went okay,
<code>false</code> if there was a problem with the profile.</p>
<h4>Notes</h4>
<p class="imquote">Currently we only support updating the EXIF
resolution and orientation.</p>
<h4>Magick API</h4>
<p>SyncImageProfiles</p>
</div>
<div class="sig">
<h3 id="texture_fill_to_border">texture_fill_to_border</h3>
<p><span class=
"arg">img</span>.texture_fill_to_border(<span class=
"arg">x</span>, <span class="arg">y</span>, <span class=
"arg">texture</span>) -> <em>image</em></p>
</div>
<div class="desc">
<h4>Description</h4>
<p>Replaces the target pixel at <span class="arg">x</span>,
<span class="arg">y</span> and its neighbors that are not the
border color with copies of the <span class=
"arg">texture</span> image. Use the <a href=
"imageattrs.html#fuzz">fuzz</a> attribute to specify how
closely a pixel must match the border color.</p>
<h4>Arguments</h4>
<dl>
<dt>x, y</dt>
<dd>The x- and y-offset of the target pixel.</dd>
<dt>texture</dt>
<dd>An image or imagelist. If an imagelist, uses the current
image.</dd>
</dl>
<h4>Returns</h4>
<p>A new image</p>
<h4>Example</h4>
<p>In this example the target is the pixel in the center of the
image. The texture - in this case a picture of a girl in a
flowered hat - replaces this pixel and its neighbors until
reaching a black pixel. Mouse over the image to see the
original image. Notice the plum-colored circles are replaced as
well. Compare this result with the result of
<code>texture_floodfill</code>, below.</p>
<p class="rollover"><a href=
"javascript:popup('texture_fill_to_border.rb.html')"><img src=
"ex/texture_fill_to_border_after.gif" alt=
"texture_fill_to_border example" onmouseover=
"this.src='ex/texture_fill_to_border_before.gif'" onmouseout=
"this.src='ex/texture_fill_to_border_after.gif'" title=
"Click to see the example script" /></a> <img src=
"ex/images/spin.gif" alt="" class="spin" style="left:206px;"
title="Mouse over the example to see the original image" /></p>
<h4>See also</h4>
<p><a href=
"image1.html#color_fill_to_border">color_fill_to_border</a>,
<a href=
"image2.html#matte_fill_to_border">matte_fill_to_border</a></p>
<h4>Magick API</h4>
<p>ColorFloodfillImage</p>
</div>
<div class="sig">
<h3 id="texture_floodfill">texture_floodfill</h3>
<p><span class="arg">img</span>.texture_floodfill(<span class=
"arg">x</span>, <span class="arg">y</span>, <span class=
"arg">texture</span>) -> <em>image</em></p>
</div>
<div class="desc">
<h4>Description</h4>
<p>Replaces the target pixel at <span class="arg">x</span>,
<span class="arg">y</span> and its neighbors that are the same
color with the <span class="arg">texture</span> image. By
default, the neighbor pixels must be exactly the same color as
the target pixel. Use the <a href=
"imageattrs.html#fuzz">fuzz</a> attribute to specify how much
difference is acceptable.</p>
<h4>Arguments</h4>
<dl>
<dt>x, y</dt>
<dd>The x- and y-offset of the target pixel.</dd>
<dt>texture</dt>
<dd>An image or imagelist. If an imagelist, uses the current
image.</dd>
</dl>
<h4>Returns</h4>
<p>A new image</p>
<h4>Example</h4>
<p>In this example the target is the pixel in the center of the
image. The texture - in this case a picture of a girl in a
flowered hat - replaces this pixel and its same-colored
neighbors. Mouse over the image to see the original image.
Notice the plum-colored circles are not replaced. Compare this
result with the result of <code>texture_fill_to_border</code>,
above.</p>
<p class="rollover"><a href=
"javascript:popup('texture_floodfill.rb.html')"><img src=
"ex/texture_floodfill_after.gif" alt=
"texture_floodfill example" onmouseover=
"this.src='ex/texture_floodfill_before.gif'" onmouseout=
"this.src='ex/texture_floodfill_after.gif'" title=
"Click to see the example script" /></a><img src=
"ex/images/spin.gif" alt="" class="spin" style="left:206px;"
title="Mouse over the example to see the original image" /></p>
<h4>See also</h4>
<p><a href="image1.html#color_floodfill">color_floodfill</a>,
<a href="image2.html#matte_floodfill">matte_floodfill</a></p>
<h4>Magick API</h4>
<p>ColorFloodfillImage</p>
</div>
<div class="sig">
<h3 id="threshold">threshold</h3>
<p><span class="arg">img</span>.threshold(<span class=
"arg">threshold</span>) -> <em>image</em></p>
</div>
<div class="desc">
<h4>Description</h4>
<p class="imquote">Changes the value of individual pixels based
on the intensity of each pixel compared to <span class=
"arg">threshold</span>. The result is a high-contrast, two
color image.</p>
<h4>Arguments</h4>
<p>A value between 0 and QuantumRange.</p>
<h4>Returns</h4>
<p>A new image</p>
<h4>Example</h4>
<p><code>threshold(MaxRGB*0.55)</code></p>
<p class="rollover"><a href=
"javascript:popup('threshold.rb.html')"><img src=
"ex/threshold.jpg" onmouseover=
"this.src='ex/images/Flower_Hat.jpg'" onmouseout=
"this.src='ex/threshold.jpg'" title=
"Click to see the example script" alt=
"threshold example" /></a><img src="ex/images/spin.gif" alt=""
class="spin" title=
"Mouse over the example to see the original image" /></p>
<h4>See also</h4>
<p><a href=
"image1.html#adaptive_threshold">adaptive_threshold</a>,
<a href="image1.html#bilevel_channel">bilevel_channel</a>,
<a href=
"#random_threshold_channel">random_threshold_channel</a></p>
<h4>Magick API</h4>
<p>ThresholdImage</p>
</div>
<div class="sig">
<h3 id="thumbnail">thumbnail</h3>
<p><span class="arg">img</span>.thumbnail(<span class=
"arg">new_width</span>, <span class="arg">new_height</span>)
-> <em>image</em><br />
<span class="arg">img</span>.thumbnail(<span class=
"arg">scale_factor</span>) -> <em>image</em></p>
</div>
<div class="desc">
<h4>Description</h4>
<p>The <code>thumbnail</code> method is a fast resizing method
suitable for use when the size of the resulting image is <
10% of the original.</p>
<h4>Arguments</h4>
<p>You can call <code>thumbnail</code> with either the new
width and height or the scale factor.</p>
<dl>
<dt>new_width, new_height</dt>
<dd>The desired width and height in pixels.</dd>
<dt>scale_factor</dt>
<dd>The desired size represented as a floating-point number.
For example, to make a thumbnail that is 9.5% of the size of
the original image, use <code>0.095</code>.</dd>
</dl>
<h4>Returns</h4>
<p>A new image</p>
<h4>Example</h4>
<pre>
img = Image.read("images/Cheetah.jpg").first
thumbnail = img.thumbnail(img.columns*0.09, img.rows*0.09)
</pre>
<h4>See also</h4>
<p><a href="image2.html#minify">minify</a>, <a href=
"#resize">resize</a>, <a href="#sample">sample</a>, <a href=
"#scale">scale</a></p>
<h4>Magick API</h4>
<p>ThumbnailImage</p>
</div>
<div class="sig">
<h3 id="thumbnail_bang">thumbnail!</h3>
<p><span class="arg">img</span>.thumbnail!(<span class=
"arg">new_width</span>, <span class="arg">new_height</span>)
-> <em>self</em><br />
<span class="arg">img</span>.thumbnail!(<span class=
"arg">scale_factor</span>) -> <em>self</em></p>
</div>
<div class="desc">
<h4>Description</h4>
<p>In-place form of <a href="#thumbnail">thumbnail</a>.</p>
<h4>Returns</h4>
<p>self</p>
</div>
<div class="sig">
<h3 id="to_blob">to_blob</h3>
<p><span class="arg">img</span>.to_blob <span class="arg">[ {
optional arguments } ]</span>-> <em>string</em></p>
</div>
<div class="desc">
<h4>Description</h4>
<p>Creates a <em>B</em>inary <em>L</em>arge <em>OB</em>ject, a
direct-to-memory version of the image. The <a href=
"image1.html#from_blob">from_blob</a> method constructs an
image from a BLOB created by this method.</p>
<h4>Arguments</h4>
<p>No required arguments, however you can specify the image
format (such as JPEG, PNG, etc.) and depth by calling the
<a href="imageattrs.html#format">format</a> and <a href=
"imageattrs.html#Image.depth">depth</a> attributes, as well as
other <a href="info.html">Image::Info</a> attributes as
appropriate, in a block associated with the method.</p>
<h4>Returns</h4>
<p>A string containing the image data represented as a
BLOB.</p>
<h4>Example</h4>
<p><a href="javascript:popup('to_blob.rb.html')"><img src=
"ex/to_blob.gif" alt="to_blob example" title=
"Click to see the example script" /></a></p>
<h4>See also</h4>
<p><a href="image1.html#from_blob">from_blob</a></p>
<h4>Magick API</h4>
<p>ImageToBlob</p>
</div>
<div class="sig">
<h3 id="to_color">to_color</h3>
<p><span class="arg">img</span>.to_color(<span class=
"arg">pixel</span>) -> <em>string</em></p>
</div>
<div class="desc">
<h4>Description</h4>
<p>Returns the color name for a pixel. Unlike the
<code>Pixel#to_color</code> method, to_color uses the <a href=
"imageattrs.html#Image.depth">depth</a> and <a href=
"imageattrs.html#Image.matte">matte</a> attributes of the image
to determine the color name.</p>
<h4>Arguments</h4>
<p>A <a href="struct.html#Pixel">Pixel</a> object.</p>
<h4>Returns</h4>
<p>A <a href="imusage.html#color_names">color name</a>.</p>
<h4>Example</h4>
<pre>
img = Image.read('ex/images/Flower_Hat.jpg').first
» ex/images/Flower_Hat.jpg JPEG 200x250 DirectClass 8-bit 9761b
pixel = img.pixel_color(img.columns/2, img.rows/2)
» #<struct Pixel red=216, green=147, blue=106, opacity=0>
img.to_color(pixel)
» "#D8936A"
</pre>
<h4>See also</h4>
<p><a href="struct.html#Pixel">Pixel#to_color</a></p>
<h4>Magick API</h4>
<p>QueryColorname</p>
</div>
<div class="sig">
<h3 id="transparent">transparent</h3>
<p><span class="arg">img</span>.transparent(<span class=
"arg">color</span>, <span class=
"arg">opacity</span>=TransparentOpacity) ->
<em>image</em></p>
</div>
<div class="desc">
<h4>Description</h4>
<p>Changes the opacity value of all the pixels that match
<span class="arg">color</span> to the value specified by
<span class="arg">opacity</span>. By default the pixel must
match exactly, but you can specify a tolerence level by setting
the <a href="imageattrs.html#fuzz">fuzz</a> attribute on the
image.</p>
<h4>Arguments</h4>
<dl>
<dt>color</dt>
<dd>Either a <a href="imusage.html#color_names">color
name</a> or a <a href="struct.html#Pixel">pixel</a>.</dd>
<dt>opacity</dt>
<dd>The new opacity value, either an <a href=
"constants.html#Opacity">opacity</a> value or a number
between 0 and QuantumRange. The default is
TransparentOpacity.</dd>
</dl>
<h4>Returns</h4>
<p>A new image</p>
<h4>Example</h4>
<p>Mouse over the image to see the original. In this example,
all the black pixels are made transparent. The resulting image
has been composited over a plasma background, which shows
through the transparent pixels.</p>
<p class="rollover"><a href=
"javascript:popup('transparent.rb.html')"><img src=
"ex/transparent_after.gif" title=
"Click to see the example script" onmouseover=
"this.src='ex/transparent_before.gif'" onmouseout=
"this.src='ex/transparent_after.gif'" alt=
"transparent example" /></a><img src="ex/images/spin.gif" alt=
"" class="spin" title=
"Mouse over the example to see the original image" /></p>
<h4>See also</h4>
<p><a href="image2.html#matte_replace">matte_replace</a>,
<a href="draw.html#matte">Draw#matte</a></p>
<h4>Magick API</h4>
<p>TransparentImage</p>
</div>
<div class="sig">
<h3 id="transpose">transpose</h3>
<p><span class="arg">img</span>.transpose ->
<em>image</em></p>
</div>
<div class="desc">
<h4>Description</h4>
<p class="imquote">Creates a horizontal mirror image by
reflecting the pixels around the central y-axis while rotating
them by 90 degrees.</p>
<h4>Returns</h4>
<p>A new image</p>
<h4>Example</h4>
<p class="rollover"><a href=
"javascript:popup('transpose.rb.html')"><img src=
"ex/transpose.jpg" alt="transpose example" title=
"Click to see the example script" onmouseover=
"this.src='ex/images/Flower_Hat.jpg'" onmouseout=
"this.src='ex/transpose.jpg'" /></a> <img src=
"ex/images/spin.gif" alt="" class="spin" style="left:252px;"
title="Mouse over the example to see the original image" /></p>
<h4>See also</h4>
<p><a href="image2.html#flip">flip</a>, <a href=
"image2.html#flop">flop</a>, <a href=
"image3.html#rotate">rotate</a>, <a href=
"#transpose_bang">transpose!</a>, <a href=
"image3.html#transverse">transverse</a></p>
<h4>Magick API</h4>
<p>TransposeImage</p>
</div>
<div class="sig">
<h3 id="transpose_bang">transpose!</h3>
<p><span class="arg">img</span>.transpose! ->
<em>self</em></p>
</div>
<div class="desc">
<h4>Description</h4>
<p>In-place form of <a href="#transpose">transpose</a>.</p>
<h4>Returns</h4>
<p>self</p>
</div>
<div class="sig">
<h3 id="transverse">transverse</h3>
<p><span class="arg">img</span>.transverse ->
<em>image</em></p>
</div>
<div class="desc">
<h4>Description</h4>
<p class="imquote">Creates a vertical mirror image by
reflecting the pixels around the central x-axis while rotating
them by 270 degrees</p>
<h4>Returns</h4>
<p>A new image</p>
<h4>Example</h4>
<p class="rollover"><a href=
"javascript:popup('transverse.rb.html')"><img src=
"ex/transverse.jpg" alt="transverse example" title=
"Click to see the example script" onmouseover=
"this.src='ex/images/Flower_Hat.jpg'" onmouseout=
"this.src='ex/transverse.jpg'" /></a> <img src=
"ex/images/spin.gif" alt="" class="spin" style="left:252px;"
title="Mouse over the example to see the original image" /></p>
<h4>See also</h4>
<p><a href="image2.html#flip">flip</a>, <a href=
"image2.html#flop">flop</a>, <a href=
"image3.html#rotate">rotate</a>, <a href=
"image3.html#transpose">transpose</a>, <a href=
"#transverse_bang">transverse!</a></p>
<h4>Magick API</h4>
<p>TransposeImage</p>
</div>
<div class="sig">
<h3 id="transverse_bang">transverse!</h3>
<p><span class="arg">img</span>.transverse! ->
<em>self</em></p>
</div>
<div class="desc">
<h4>Description</h4>
<p>In-place form of <a href="#transverse">transverse</a>.</p>
<h4>Returns</h4>
<p>self</p>
</div>
<div class="sig">
<h3 id="trim">trim</h3>
<p><span class="arg">img</span>.trim(<span class=
"arg">reset</span>=false) -> <em>image</em></p>
</div>
<div class="desc">
<h4>Description</h4>
<p class="imquote">Removes the edges that are exactly the same
color as the corner pixels. Use the <a href=
"imageattrs.html#fuzz">fuzz</a> attribute to make
<code>trim</code> remove edges that are nearly the same color
as the corner pixels.</p>
<h4>Arguments</h4>
<p>The trim method retains the offset information in the
cropped image. This may cause the image to appear to be
surrounded by blank or black space when viewed with an external
viewer. This only occurs when the image is saved in a format
(such as GIF) that saves offset information. To reset the
offset data, use true as the argument to trim. See also
<a href="image1.html#crop">crop</a>.</p>
<h4>Returns</h4>
<p>A new image</p>
<h4>Example</h4>
<p class="rollover"><a href=
"javascript:popup('trim.rb.html')"><img src="ex/trim_after.jpg"
onmouseover="this.src='ex/trim_before.jpg'" onmouseout=
"this.src='ex/trim_after.jpg'" alt="trim example" title=
"Click to see the example script" /></a> <img src=
"ex/images/spin.gif" alt="" class="spin" title=
"Mouse over the image to see the original image" /></p>
<h4>See also</h4>
<p><a href="image1.html#crop">crop</a></p>
<h4>Magick API</h4>
<p>CropImage</p>
</div>
<div class="sig">
<h3 id="trim_bang">trim!</h3>
<p><span class="arg">img</span>.trim!(<span class=
"arg">reset</span>=false) -> <em>self</em></p>
</div>
<div class="desc">
<p>In-place form of <a href="#trim">trim</a>.</p>
<h4>Returns</h4>
<p>self</p>
</div>
<div class="sig">
<h3 id="unique_colors">unique_colors</h3>
<p><span class="arg">img</span>.unique_colors ->
<em>image</em></p>
</div>
<div class="desc">
<h4>Description</h4>
<p>Constructs a new image with one pixel for each unique color
in the image. The new image has 1 row. The row has 1 column for
each unique pixel in the image.</p>
<h4>Returns</h4>
<p>A new image</p>
<h4>Magick API</h4>
<p>UniqueImageColors</p>
</div>
<div class="sig">
<h3 id="unsharp_mask">unsharp_mask</h3>
<p><span class="arg">img</span>.unsharp_mask(<span class=
"arg">radius=0.0</span>, <span class="arg">sigma=1.0</span>,
<span class="arg">amount=1.0</span>, <span class=
"arg">threshold=0.05</span>) -> <em>image</em></p>
</div>
<div class="desc">
<h4>Description</h4>
<p class="imquote">Sharpens an image. We convolve the image
with a Gaussian operator of the given <span class=
"arg">radius</span> and standard deviation (<span class=
"arg">sigma</span>). For reasonable results, <span class=
"arg">radius</span> should be larger than <span class=
"arg">sigma</span>. Use a radius of 0 and
<code>unsharp_mask</code> selects a suitable radius for
you.</p>
<h4>Arguments</h4>
<p>All arguments are optional.</p>
<dl>
<dt>radius</dt>
<dd>The radius of the Gaussian operator. The default is
0.0.</dd>
<dt>sigma</dt>
<dd>The standard deviation of the Gaussian operator. A good
starting value is 1.0, which is the default.</dd>
<dt>amount</dt>
<dd>The percentage of the blurred image to be added to the
receiver, specified as a fraction between 0 and 1.0. A good
starting value is 1.0, which is the default.</dd>
<dt>threshold</dt>
<dd>The threshold needed to apply the amount, specified as a
fraction between 0 and 1.0. A good starting value is 0.05,
which is the default.</dd>
</dl>
<h4>Returns</h4>
<p>A new image</p>
<h4>Example</h4>
<p><a href=
"javascript:popup:('unsharp_mask.rb.html')"><img src="ex/unsharp_mask.jpg"
alt="unsharp_mask example" title=
"Click to see the example script" /></a></p>
<h4>See also</h4>
<p><a href="image2.html#enhance">enhance</a>, <a href=
"image2.html#median_filter">median_filter</a>, <a href=
"image3.html#reduce_noise">reduce_noise</a>, <a href=
"#unsharp_mask_channel">unsharp_mask_channel</a></p>
<h4>Magick API</h4>
<p>UnsharpMaskImage</p>
</div>
<div class="sig">
<h3 id="unsharp_mask_channel">unsharp_mask_channel</h3>
<p><span class=
"arg">img</span>.unsharp_mask_channel(<span class=
"arg">radius=0.0</span>, <span class="arg">sigma=1.0</span>,
<span class="arg">amount=1.0</span>, <span class=
"arg">threshold=0.05</span> [,<span class=
"arg">channel</span>...]) -> <em>image</em></p>
</div>
<div class="desc">
<h4>Description</h4>
<p class="imquote">Sharpens an image. We convolve the image
with a Gaussian operator of the given <span class=
"arg">radius</span> and standard deviation (<span class=
"arg">sigma</span>). For reasonable results, <span class=
"arg">radius</span> should be larger than <span class=
"arg">sigma</span>. Use a radius of 0 and
<code>unsharp_mask_channel</code> selects a suitable radius for
you.</p>
<p>Only the specified channels are sharpened.</p>
<h4>Arguments</h4>
<p>All arguments are optional.</p>
<dl>
<dt>radius</dt>
<dd>The radius of the Gaussian operator. The default is
0.0.</dd>
<dt>sigma</dt>
<dd>The standard deviation of the Gaussian operator. A good
starting value is 1.0, which is the default.</dd>
<dt>amount</dt>
<dd>The percentage of the blurred image to be added to the
receiver, specified as a fraction between 0 and 1.0. A good
starting value is 1.0, which is the default.</dd>
<dt>threshold</dt>
<dd>The threshold needed to apply the amount, specified as a
fraction between 0 and 1.0. A good starting value is 0.05,
which is the default.</dd>
<dt>channel...</dt>
<dd>0 or more <a href=
"constants.html#ChannelType">ChannelType</a> arguments. If no
channels are specified, all the channels are sharpened. This
is the equivalent of <a href=
"#unsharp_mask">unsharp_mask</a>.</dd>
</dl>
<h4>Returns</h4>
<p>A new image</p>
<h4>See also</h4>
<p><a href="image2.html#enhance">enhance</a>, <a href=
"image2.html#median_filter">median_filter</a>, <a href=
"image3.html#reduce_noise">reduce_noise</a>, <a href=
"#unsharp_mask">unsharp_mask</a></p>
<h4>Magick API</h4>
<p>UnsharpMaskImageChannel</p>
</div>
<div class="sig">
<h3 id="view">view</h3>
<p><span class="arg">img</span>.view(<span class=
"arg">x</span>, <span class="arg">y</span>, <span class=
"arg">width</span>, <span class="arg">height</span>) ->
<em>aView</em><br />
<span class="arg">img</span>.view(<span class="arg">x</span>,
<span class="arg">y</span>, <span class="arg">width</span>,
<span class="arg">height</span>) { |view|
<em>block</em> } -> <em>nil</em></p>
</div>
<div class="desc">
<h4>Description</h4><code>View</code> is a convenience method
that supports getting and setting individual image pixels by
<code>[i][j]</code> coordinates. With no associated block,
<code>view</code> returns an <a href=
"struct.html#view">Image::View</a> object. If the optional code
block is given, it will be passed the <code>Image::View</code>
object as an argument. The <a href=
"struct.html#view_sync">sync</a> method will be called
automatically when the block terminates. In this case,
<code>view</code> returns <code>nil</code>.
<h4>Arguments</h4>
<dl>
<dt>x, y</dt>
<dd>The offset of the view from the top-left corner of the
image. Within the view, pixels are relative to the top-left
corner of the view, <em>not</em> the image.</dd>
<dt>width, height</dt>
<dd>The width and height of the view. The view may not extend
past the boundaries of <span class="arg">img</span>.</dd>
</dl>
<h4>Returns</h4>
<p>If the optional code block is present, <code>view</code>
returns <code>nil</code>. If it is not present,
<code>view</code> returns an <code>Image::View</code>
object.</p>
<h4>See</h4>
<p><a href="struct.html#view">Image::View</a></p>
<h4>Examples</h4>
<p>The example image below has been scaled 500% for
clarity.</p>
<p><a href="javascript:popup('viewex.rb.html')"><img src=
"ex/viewex.gif" title="Click to see the example script" alt=
"view example" /></a></p>
<pre>
img = Image.new(40, 40) {self.background_color = 'lightcyan2'}
# The view is 400 pixels square, starting at
# column 10, row 5 from the top of the image.
img.view( 10, 5, 20, 20) do |view|
# Set all the pixels in the view to green.
view[][] = Pixel.new(0, QuantumRange)
# Change the top and bottom rows to red.
view[0][] = 'red'
view[-1,1][] = 'red'
# Set 6 pixels to black.
view[[13,15]][[12,14,16]] = 'black'
# Set 1 pixel to yellow.
view[5][7] = 'yellow'
# Change the green channel of all the
# pixels on row 8.
view[8][].green = QuantumRange/2
# Change the blue channel of 8 pixels
# on column 10.
view[4,8][10].blue = QuantumRange
end
</pre>
<h4>See also</h4>
<p><a href="image3.html#pixel_color">pixel_color</a>, <a href=
"image2.html#get_pixels">get_pixels</a>, <a href=
"#store_pixels">store_pixels</a></p>
<h4>Notes</h4>
<p>The <code>view</code> method introduces a relatively high
level of overhead to pixel manipulation compared to methods
that use the ImageMagick API to identify and change pixels. I
recommend that you use <code>view</code> only when the number
of pixels identified in the view is fairly small (a few
thousand to a few hundred thousand, depending on your patience
and the speed of your computer) and you need this degree of
control.</p>
</div>
<div class="sig">
<h3 id="vignette">vignette</h3>
<p><span class="arg">img</span>.vignette(<span class=
"arg">x</span>, <span class="arg">y</span>, <span class=
"arg">radius</span>=0.0, <span class="arg">sigma</span>=10.0)
-> <span class="arg">image</span></p>
</div>
<div class="desc">
<h4>Description</h4>
<p>Gradually shades the edges of the image by transforming the
pixels into the background color.</p>
<h4>Arguments</h4>
<dl>
<dt>x</dt>
<dd>Influences the amount of background color in the
horizontal dimension. Larger values of <span class=
"arg">x</span> make the vignette narrower. This argument
should be positive and less than image.columns / 2. This
argument is optional. If omitted, the default value is 0.10 *
<span class="arg">img</span>.columns.</dd>
<dt>y</dt>
<dd>Influences the amount of background color in the vertical
dimension. Larger values of <span class="arg">y</span> make
the vignette shorter. This argument should be positive and
less than image.rows / 2. This argument is optional. If
omitted, the default value is 0.10 * <span class=
"arg">img</span>.rows.</dd>
<dt>radius, sigma</dt>
<dd>Controls the amount of blurring. Larger values of
<span class="arg">sigma</span> increase the blurring at the
expense of increased execution time. In general, <span class=
"arg">radius</span> should be larger than <span class=
"arg">sigma</span>, although if <span class=
"arg">radius</span> is 0 then ImageMagick will choose a
suitable value. <span class="arg">Sigma</span> must be
non-zero. Choose a very small value for <span class=
"arg">sigma</span> to produce a "hard" edge.</dd>
</dl>
<h4>Returns</h4>
<p>A new image</p>
<h4>Example</h4>
<p class="rollover"><a href=
"javascript:popup('vignette.rb.html')"><img src=
"ex/vignette.jpg" alt="vignette example" title=
"Click to see the example script" onmouseover=
"this.src='ex/images/Flower_Hat.jpg'" onmouseout=
"this.src='ex/vignette.jpg'" /></a> <img src=
"ex/images/spin.gif" alt="" class="spin" title=
"Mouse over the example to see the original image" /></p>
<h4>Magick API</h4>
<p>VignetteImage</p>
<h4>Notes</h4>
<p>The image produced by <code>vignette</code> is very similar
to the image produced by RMagick's vignette.rb example script.
However, the example script gives you more control over the
size, shape, and background color of the vignette.</p>
</div>
<div class="sig">
<h3 id="watermark">watermark</h3>
<p><span class="arg">img</span>.watermark(<span class=
"arg">mark</span>, <span class="arg">lightness</span>=1.0,
<span class="arg">saturation</span>=1.0, <span class=
"arg">x_offset</span>=0, <span class="arg">y_offset</span>=0)
-> <em>image</em><br />
<span class="arg">img</span>.watermark(<span class=
"arg">mark</span>, <span class="arg">lightness</span>=1.0,
<span class="arg">saturation</span>=1.0, <span class=
"arg">gravity</span>, <span class="arg">x_offset</span>=0,
<span class="arg">y_offset</span>=0) -> <em>image</em></p>
</div>
<div class="desc">
<h4>Description</h4>
<p>Composites a watermark image on the target image using the
<a href="constants.html#CompositeOperator">Modulate</a>
composite operator. This composite operation operates in the
HSL colorspace and combines part of the lightness, part of the
saturation, and all of the hue of each pixel in the watermark
with the corresponding pixel in the target image</p>
<h4>Arguments</h4>
<dl>
<dt>mark</dt>
<dd>The watermark image. Either an imagelist or an image. If
an imagelist, uses the current image.</dd>
<dt>lightness</dt>
<dd>The fraction of the lightness component of the watermark
pixels to be composited onto the target image. Must be a
non-negative number or a string in the form "NN%". If
lightness is a number it is interpreted as a percentage. Both
0.25 and "25%" mean 25%. The default is 100%.</dd>
<dt>saturation</dt>
<dd>The fraction of the saturation component of the watermark
pixels to be composited onto the target image. Must be a
non-negative number or a string in the form "NN%". If
lightness is a number it is interpreted as a percentage. Both
0.25 and "25%" mean 25%. The default is 100%.</dd>
<dt>x_offset</dt>
<dd>The offset of the watermark, measured from the left-hand
side of the target image. The default is 0.</dd>
<dt>y_offset</dt>
<dd>The offset of the watermark, measured from the top of the
target image. The default is 0.</dd>
</dl>
<p>Watermark can be called with a <span class=
"arg">gravity</span> argument or without. When a <span class=
"arg">gravity</span> argument is specified but the <span class=
"arg">x-</span> and <span class="arg">y-offsets</span> are
omitted, the watermark is positioned based on the value of the
<span class="arg">gravity</span> argument:</p>
<dl>
<dt>NorthWestGravity</dt>
<dd>The watermark abuts the top and left sides of the
image.</dd>
<dt>NorthGravity</dt>
<dd>The watermark is centered left-to-right and abuts the top
of the image.</dd>
<dt>NorthEastGravity</dt>
<dd>The watermark abuts the top and right sides of the
image.</dd>
<dt>EastGravity</dt>
<dd>The watermark is centered top-to-bottom and abuts the
right side of the image.</dd>
<dt>SouthEastGravity</dt>
<dd>The watermark abuts the bottom and right sides of the
image.</dd>
<dt>SouthGravity</dt>
<dd>The watermark is centered left-to-right and abuts the
bottom of the image.</dd>
<dt>SouthWestGravity</dt>
<dd>The watermark abuts the bottom and left sides of the
image.</dd>
<dt>WestGravity</dt>
<dd>The watermark is centered top-to-bottom and abuts the
left side of the image.</dd>
<dt>CenterGravity</dt>
<dd>The watermark is centered left-to-right and
top-to-bottom.</dd>
</dl>
<p>When the <span class="arg">gravity</span> argument is
present and the <span class="arg">x-offset</span> (and
optionally the <span class="arg">y-offset</span>) is present,
the <span class="arg">x-</span> and <span class=
"arg">y-offset</span> are measured from the right and/or bottom
edges of the target image based on the value of <span class=
"arg">gravity</span>. If the argument is NorthEastGravity,
EastGravity, or SouthEastGravity, the <span class=
"arg">x-offset</span> is measured from the right side of the
image. If the argument is SouthEastGravity, SouthGravity, or
SouthWestGravity, the <span class="arg">y-offset</span> is
measured from the bottom of the image. All other values are
ignored and the <span class="arg">x-</span> and <span class=
"arg">y-offset</span> are measured from the upper-left corner
of the image.</p>
<h4>Returns</h4>
<p>A new image</p>
<h4>Example</h4>
<p>See <a href=
"http://www.cit.gu.edu.au/~anthony/graphics/imagick6/annotating/#wmark_image">
"Watermarking with Images"</a> in Anthony Thyssen's <a href=
"http://www.cit.gu.edu.au/~anthony/graphics/imagick6/"><cite>Examples
of ImageMagick Usage</cite></a>.</p>
<p class="rollover"><a href=
"javascript:popup('watermark.rb.html')"><img src=
"ex/watermark.jpg" alt="watermark example" title=
"Click to see the example script" onmouseover=
"this.src='ex/images/Flower_Hat.jpg'" onmouseout=
"this.src='ex/watermark.jpg'" /></a> <img src=
"ex/images/spin.gif" alt="" class="spin" title=
"Mouse over the example to see the original image" /></p>
<h4>See also</h4>
<p><a href="image1.html#composite">composite</a>, <a href=
"#stegano">stegano</a></p>
</div>
<div class="sig">
<h3 id="wave">wave</h3>
<p><span class="arg">img</span>.wave(<span class=
"arg">amplitude</span>=25.0, <span class=
"arg">wavelength</span>=150.0) -> <em>image</em></p>
</div>
<div class="desc">
<h4>Description</h4>
<p class="imquote">Creates a "ripple" effect in the image by
shifting the pixels vertically along a sine wave whose
<span class="arg">amplitude</span> and <span class=
"arg">wavelength</span> is specified by the given
parameters.</p>
<h4>Returns</h4>
<p>A new image</p>
<h4>Example</h4>
<p class="rollover"><a href="javascript:popup('wave.rb.html')">
<!-- This img tag displays the original image when the mouse is over -->
<img style=
"padding-top:25px; padding-bottom:25px; display:none" id=
"nowave" title="Click to see the example script" onmouseout=
"this.style.display='none'; waved.style.display='';" src=
"ex/images/Flower_Hat.jpg" alt="wave example" /> <!--
This img tag displays the framed image when the mouse is not over
--><img class="hide"
id="waved" onmouseover=
"this.style.display='none'; nowave.style.display='';" src=
"ex/wave.jpg" alt="wave example" /></a> <img src=
"ex/images/spin.gif" alt="" class="spin" title=
"Mouse over the example to see the original image" /></p>
<h4>Magick API</h4>
<p>WaveImage</p>
<h4>See also</h4>
<p><a href=
"imageattrs.html#virtual_pixel_method">virtual_pixel_method</a></p>
</div>
<div class="sig">
<h3 id="wet_floor">wet_floor</h3>
<p><span class="arg">img</span>.wet_floor(<span class=
"arg">intial=0.5</span>, <span class="arg">rate=1.0</span>)
-> <em>image</em></p>
</div>
<div class="desc">
<h4>Description</h4>
<p>Creates a <a href=
"http://en.wikipedia.org/wiki/Wet_floor_effect">"wet floor"</a>
reflection. The reflection is an inverted copy of the image
that changes from partially transparent to entirely
transparent. By default only the bottom third of the image
appears in the reflection.</p>
<p>Note that the output image is just the reflection. This
makes it easy to apply further transformations to the
reflection before combining it with the original image.</p>
<h4>Arguments</h4>
<dl>
<dt>initial</dt>
<dd>A value between 0.0 and 1.0 that specifies the initial
percentage of transparency. Higher values cause the top of
the reflection to be more transparent, lower values less
transparent. The default is 0.5, which means that the top of
the reflection is 50% transparent.</dd>
<dt>rate</dt>
<dd>A non-negative value that specifies how rapidly the
reflection transitions from the initial level of transparency
to entirely transparent. The default value is 1.0, which
means that the transition occurs in 1/3 the image height.
Values greater than 1.0 speed up the transition (the
reflection will have fewer rows), values lower than 1.0 slow
down the transition (the reflection will have more rows). A
value of 0.0 means that the level of transparency will not
change.</dd>
</dl>
<h4>Returns</h4>
<p>A new image</p>
<h4>Example</h4>
<p>Here are four examples of <code>wet_floor</code>. The top
image shows the result of appending the default reflection to
the original image. The second image shows the result of
decreasing the initial transparency to 0.25 and using 0.5 as
the <span class="arg">rate</span> argument. The third image
uses the same reflection as the second image but has a slant
added. The bottom image is the same as the third image but with
a ripple effect.</p>
<p><a href="javascript:popup('wet_floor.rb.html')"><img src=
"ex/wet_floor.gif" title="Click to see the example script" alt=
"wet floor example" /></a></p>
</div>
<div class="sig">
<h3 id="white_threshold">white_threshold</h3>
<p><span class="arg">img</span>.white_threshold(<span class=
"arg">red_channel</span> [, <span class=
"arg">green_channel</span>[, <span class=
"arg">blue_channel</span>[, <span class=
"arg">opacity_channel</span>]]]) -> <em>image</em></p>
</div>
<div class="desc">
<h4>Description</h4>
<p class="imquote">Forces all pixels above the threshold into
white while leaving all pixels below the threshold
unchanged.</p>
<h4>Arguments</h4>
<p>Each channel argument is a number between 0 and
QuantumRange. All arguments except the first may be omitted. If
the <span class="arg">green_channel</span> or <span class=
"arg">blue_channel</span> argument is omitted, the default
value is the <span class="arg">red_channel</span> value. If the
<span class="arg">opacity_channel</span> argument is omitted,
the default value is <a href=
"constants.html#Opacity">OpaqueOpacity</a>.</p>
<h4>Returns</h4>
<p>A new image</p>
<h4>See also</h4>
<p><a href="image1.html#black_threshold">black_threshold</a>,
<a href="image1.html#bilevel_channel">bilevel_channel</a></p>
<h4>Magick API</h4>
<p>WhiteThresholdImage</p>
</div>
<div class="sig">
<h3 id="write">write</h3>
<p><span class="arg">img</span>.write(<span class=
"arg">filename</span>) <span class="arg">[ { optional arguments
} ]</span> -> <em>self</em><br />
<span class="arg">img</span>.write(<span class=
"arg">file</span>) <span class="arg">[ { optional arguments }
]</span> -> <em>self</em></p>
</div>
<div class="desc">
<h4>Description</h4>
<p>Writes the image to the specified file. ImageMagick
determines image format from the <a href=
"imusage.html#formats">prefix or extension</a>.</p>
<p>If the argument is an open file, ImageMagick will write the
image in its current format. You can force a different format
by setting the image's <a href=
"imageattrs.html#Image.format">format</a> attribute.</p>
<h4>Arguments</h4>
<p>A file name or open file object. You may also specify
optional arguments by setting <a href=
"info.html">Image::Info</a> attributes in an associated
block.</p>
<h4>Returns</h4>
<p><code>self</code>, or <code>nil</code> if the image format
cannot be determined.</p>
<h4>Example</h4>
<p>Almost all of the examples call <code>write</code>.</p>
<h4>See also</h4>
<p><a href="ilist.html#write">ImageList#write</a></p>
<h4>Magick API</h4>
<p>WriteImage</p>
</div>
<p class="spacer"> </p>
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