Codebrawl #2

output.png

solution.rb

require 'chunky_png'

class Pixelizer
  attr_reader :image, :block_width, :block_height
  
  def initialize(image, block_width, block_height)
    @image = image
    @block_width = block_width
    @block_height = block_height
  end
  
  def pixelize!
    each_block do |canvas, x, y|
      color = average_color canvas
      image.rect x, y, x + canvas.width, y + canvas.height, color, color
    end
  end
  
  private
  
  def average_color(canvas)
    sum_r, sum_g, sum_b = 0, 0, 0
    canvas.pixels.each do |pixel|
      sum_r += ChunkyPNG::Color.r pixel
      sum_g += ChunkyPNG::Color.g pixel
      sum_b += ChunkyPNG::Color.b pixel
    end
    area = canvas.area
    ChunkyPNG::Color.rgb(sum_r / area, sum_g / area, sum_b / area)
  end

  def each_block
    rows = (image.height.to_f / block_height).ceil
    cols = (image.width.to_f / block_width).ceil

    rows.times do |row|
      cols.times do |col|
        x, y = col * block_width, row * block_height
        width = [block_width, image.width - x].min
        height = [block_height, image.height - y].min
        yield image.crop(x, y, width, height), x, y
      end
    end
  end
end

image = ChunkyPNG::Image.from_file('input.png')
Pixelizer.new(image, 10, 10).pixelize!
image.save('output.png')