ChunkyPNG nearest-neighbor resize

bassie.png

bassie_resized_0.5.png

bassie_resized_2.png

chunkypng_resize.rb

require 'chunky_png'

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

[2,0.5].each do |scale|
  resized_image = ChunkyPNG::Image.new((image.width * scale).round, (image.height * scale).round)

  resized_image.pixels.map!.with_index do |pixel, index|
    x, y = index % resized_image.width, (index / resized_image.width).floor
    image[x / scale, y / scale]
  end

  resized_image.save("bassie_resized_#{scale}.png")
end

Please let me know if you know any way of improving this, was having some trouble converting the pixels' indexes to x/y coordinates. :)

I already implemented nearest neighbor resampling in ChunkyPNG: https://github.com/wvanbergen/chunky_png/blob/master/lib/chunky_png/canvas/resampling.rb

My code is significantly more complex then yours though, so patch so simplify it would be appreciated. Are you tackling bicubic resampling next? ;)