Pixelizer for CodeBrawl

output.png

pixelizer.rb

#!/usr/bin/env ruby
begin
  require 'chunky_png'
rescue LoadError
  require 'rubygems'
  require 'chunky_png'
end

class Pixelizer
  def initialize(source, chunkSize = 10)
    @source = ChunkyPNG::Image.from_file(source)
    @output = ChunkyPNG::Image.new(@source.width, @source.height)
    @size = chunkSize
  end

  def pixelize
    (0...@source.width).step(@size) do |x|
      (0...@source.height).step(@size) do |y|
        color = average_of_area(x, y)
        @output.rect(x, y, x + @size, y + @size, color, color)
      end
    end
  end

  def in_bounds?(x,y)
    x.between?(0, @source.width) && y.between?(0, @source.height)
  end

  def save(file)
    @output.save(file)
  end

  private
  def average_of_area(x, y)
    colors = {:r => [], :g => [], :b => []}

    x.upto(x + @size) do |_x|
      y.upto(y + @size) do |_y|
        next unless in_bounds?(_x, _y)
        pixel = @source.get_pixel(_x, _y)
        colors.each_key { |c| colors[c] << ChunkyPNG::Color.send(c, pixel) }
      end
    end

    color = ChunkyPNG::Color.rgb(
      average_of_color(colors[:r]),
      average_of_color(colors[:g]),
      average_of_color(colors[:b])
    )
  end

  def average_of_color(values)
    return 0 unless values.size > 0
    values.inject { |s,e| s + e } / values.size
  end
end

p = Pixelizer.new('input.png')
p.pixelize
p.save('output.png')