Sha256: 28910474b77f536a598f4485c52cb339061f497da9b52f884955109b70658b4c
Contents?: true
Size: 1.31 KB
Versions: 38
Compression:
Stored size: 1.31 KB
Contents
#! /usr/local/bin/ruby -w
require 'RMagick'
include Magick
NUM_COLORS = 256
HIST_HEIGHT = 200
img = Image.read('images/Hot_Air_Balloons_H.jpg').first
img = img.quantize(NUM_COLORS)
begin
hist = img.color_histogram
rescue NotImplementedError
img = Image.read('images/notimplemented.gif').first
img.write('color_histogram.gif')
exit
end
# sort pixels by increasing count
begin
pixels = hist.keys.sort_by {|pixel| hist[pixel] }
rescue NameError # No sort_by?
pixels = hist.keys.sort { |p, q| hist[p] <=> hist[q] }
end
scale = HIST_HEIGHT / (hist.values.max*1.025) # put 2.5% air at the top
gc = Draw.new
gc.stroke_width(1)
gc.affine(1, 0, 0, -scale, 0, HIST_HEIGHT)
# handle images with fewer than NUM_COLORS colors
start = NUM_COLORS - img.number_colors
pixels.each { |pixel|
gc.stroke(pixel.to_color)
gc.line(start, 0, start, hist[pixel])
start = start.succ
}
hatch = HatchFill.new("white", "gray95")
canvas = Image.new(NUM_COLORS, HIST_HEIGHT, hatch)
gc.draw(canvas)
text = Draw.new
text.annotate(canvas, 0, 0, 0, 20, "Color Frequency\nHistogram") {
self.pointsize = 10
self.gravity = NorthGravity
self.stroke = 'transparent'
}
canvas.border!(1, 1, "white")
canvas.border!(1, 1, "black")
canvas.border!(3, 3, "white")
#canvas.display
canvas.write("color_histogram.gif")
exit
Version data entries
38 entries across 38 versions & 1 rubygems