Codebrawl #2 entry

output.png

solution.rb

require 'chunky_png'

module ChunkyPNG
  class Image
    def pixelize!(size=10)
      [[:row, height], [:column, width]].each do |orientation, length|
        for i in 0...length
          pixelated = []; send(orientation, i).each_slice(size) do |slice|
            pixelated += [Color.rgba(*[:r,:g,:b,:a].map{|chan| 
              (slice.map{|c| Color.send(chan, c)}.inject(0.0){|sum, v| sum += v} / slice.length).round
            })] * slice.length
          end
          send("replace_#{orientation}!", i, pixelated)
        end
      end
    end
  end
end

image = ChunkyPNG::Image.from_file('input.png')
image.pixelize!
image.save('output.png')