Codebrawl #2 Entry

output.png

pixelate.rb

require 'rubygems'
require 'chunky_png'

include ChunkyPNG

BLOCK_SIZE = 10

def main in_file = 'input.png', out_file = 'output.png'
  image = Image.from_file in_file
  
  0.step(image.width, BLOCK_SIZE) do |x|
    0.step(image.height, BLOCK_SIZE) do |y|

      section = image.safe_crop x, y, BLOCK_SIZE, BLOCK_SIZE

      unless section.pixels.length <= 0
        section.fill Color.rgb_average(*section.pixels)
        image.replace! section, x, y
      end

    end
  end
  
  image.save out_file
end

class Canvas
  def safe_crop x, y, crop_width, crop_height
    crop_width = [crop_width, self.width - x].min
    crop_height = [crop_height, self.height - y].min
    
    self.crop x, y, crop_width, crop_height
  end

  def fill color
    self.rect 0, 0, self.width-1, self.height-1, ChunkyPNG::Color::TRANSPARENT, color
  end
end

module Color
  def rgb_average *args
    r, g, b = [args.map{|c| r(c)}, args.map{|c| g(c)}, args.map{|c| b(c)}].map &:average
    rgb(r, g, b)
  end
end

class Array
  def average
    return self.inject(:+) / self.length
  end
end

main