Codebrawl #2 - Pixelizing an image with ChunkyPNG

output.png

pixelize.rb

require 'chunky_png'

module ChunkyPNG::Color
  def self.average(pixels)
    new_r = pixels.map{|p| r(p)}.inject(&:+) / pixels.size
    new_g = pixels.map{|p| g(p)}.inject(&:+) / pixels.size
    new_b = pixels.map{|p| b(p)}.inject(&:+) / pixels.size
    rgb(new_r,new_g,new_b)
  end
end

class BlockyImage < ChunkyPNG::Image

  def block(x,y,n)
    positions = block_positions(x,y,n)
    positions.map{|x,y| get_pixel(x,y)}
  end

  def set_block(x,y,n,color)
    positions = block_positions(x,y,n)
    positions.map{|x,y| set_pixel(x,y,color)}
  end

  def pixelize(n)
    xtimes = (width / n.to_f).ceil
    ytimes = (height / n.to_f).ceil
    
    positions = (0...xtimes).map{|x| x * n}.product((0...ytimes).map{|y| y * n})

    positions.each do |x,y| 
      color = ChunkyPNG::Color.average(block(x, y, n))
      set_block(x, y, n, color)     
    end
  end

  private
  
  def block_positions(x,y,n)
    nx = [width, x + n].min
    ny = [height, y + n].min
    (x...nx).to_a.product((y...ny).to_a)  
  end
end

image = BlockyImage.from_file('input.png')
image.pixelize(10)
image.save('output.png')