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Versions: 4
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Contents
#
# Histogram.
#
# Calculates the histogram of an image.
# A histogram is the frequency distribution
# of the gray levels with the number of pure black values
# displayed on the left and number of pure white values on the right.
#
attr_reader :hist
def setup
size(640, 360)
# Load an image from the data directory
# Load a different image by modifying the comments
img = loadImage("frontier.jpg")
image(img, 0, 0)
@hist = Array.new(256, 0)
# Calculate the histogram
(0 ... img.width).each do |i|
(0 ... img.height).each do |j|
bright = (brightness(get(i, j))).to_i
hist[bright] += 1
end
end
# Find the largest value in the histogram using processings max function
# that's why we use to java cinversion
histMax = max(hist.to_java Java::int)
stroke(255)
# Draw half of the histogram (skip every second value)
(0 ... img.width).step(2) do |i|
# Map i (from 0..img.width) to a location in the histogram (0..255)
which = (map(i, 0, img.width, 0, 255)).to_i
# Convert the histogram value to a location between
# the bottom and the top of the picture
y = (map(hist[which], 0, histMax, img.height, 0)).to_i
line(i, img.height, i, y)
end
end
Version data entries
4 entries across 4 versions & 1 rubygems