Twitterで圧縮されにくいアイコン生成

heavy.rb

require 'RMagick'

include Magick

depth = 16
range = (1 << depth) - 1

orig_size = 48
if ARGV.length > 0
  orig_img = Image.read(ARGV[0]).first
  orig_img.set_channel_depth(AllChannels, depth)
  orig_img = orig_img.resize_to_fill(orig_size)
else
  orig_img = Image.new(orig_size, orig_size) do
    self.depth = depth
  end
  (0...orig_size).each do |y|
    (0...orig_size).each do |x|
      orig_img.pixel_color(x, y, Pixel.new(*(0...3).map { Random.rand(range) }))
    end
  end
end

mag = 7
size = orig_size * mag
img = Image.new(size, size) do
  self.depth = depth
end
rng = Random.new
(0...orig_size).each do |oy|
  (0...orig_size).each do |ox|
    orig_pixel = orig_img.pixel_color(ox, oy)
    orig_vals = [:red, :green, :blue].map {|c| orig_pixel.send(c) }
    ranges = orig_vals.map {|v| [v, range-v].min }
    (0...mag).each do |my|
      (0...mag).each do |mx|
        mag_vals = (0...3).map do |i|
          r = ranges[i]
          orig_vals[i] + rng.rand(-r..r)
        end
        img.pixel_color(ox*mag+mx, oy*mag+my, Pixel.new(*mag_vals))
      end
    end
  end
end
img.write("heavy.png")