Code Brawl - Pixelizing images with ChunkyPNG

output.png

solution.rb

require 'chunky_png'

image = ChunkyPNG::Image.from_file('input.png')

chunks = [] #the tuples we're going to operate on [start-x, start-y, delta-x, delta-y]

chunk_size = 10 #how many square pixels per normal sized chunk

#dimensions
w = image.dimension.width
h = image.dimension.height

#remainders
wr = w % chunk_size
hr = h % chunk_size

#limits
hl = h - hr
wl = w - wr

#grab each square chunk
(0..(w-wr-chunk_size)).step(chunk_size).each do |x|
	(0..(h-hr-chunk_size)).step(chunk_size).each do |y|
		chunks << [x, y, chunk_size, chunk_size] 
	end
	
	#if there's a remainder on the Y axis, add that
	if hr > 0
		chunks << [x, hl, chunk_size, hr] #odd height chunk
	end
end

#if there's a remainder on the X axis
if wr > 0
	(0..(h-hr-chunk_size)).step(chunk_size).each do |y|
		chunks << [wl, y, wr, chunk_size] #odd width chunk
	end
	if hr > 0 #remainder on both X and Y
		chunks << [wl, hl, wr, hr] #bottom right corner chunk, odd width and height
	end
end

chunks.each do |chunk|
	c_r = c_g = c_b = 0
	x,y,dx,dy = chunk
	pixels = dx*dy
	#sum the indvidual color values for all pixels in the chunk
	(x..(x + dx - 1)).each do |a|
		(y..(y + dy - 1)).each do |b|
			c_r += ChunkyPNG::Color.r(image[a,b])
			c_g += ChunkyPNG::Color.g(image[a,b])
			c_b += ChunkyPNG::Color.b(image[a,b])
		end
	end
	#divide by total number of pixels
	c_r /= pixels
	c_g /= pixels
	c_b /= pixels
	color = ChunkyPNG::Color.rgb(c_r,c_g,c_b) #color to set the chunk to
	(x..(x + dx - 1)).each do |a|
		(y..(y + dy - 1)).each do |b|
			image[a,b] = color
		end
	end
end

image.save('output.png')