# Convert png image to 256 palette image for Pokitto. Usage:
#
#   python convert_png.py input_image.png palette_16x16_image.png
#
# The script will read the input PNG image (must be in RGB format, NOT
# indexed), match each pixel to the closest color in the palette and output
# the image to stdout as an array of bytes, by columns. It's best if the image
# is made only of color of the palette as the closest match can sometimes look
# different from what you imagined.
#
# The script will also create an image (out.png) of the converted image, so
# that you can check how it looks.
#
# author: Miloslav Ciz
# license: CC0

import sys
from PIL import Image

def findClosest(pixel, palettePixels):
  result = 0
  closestDist = 255 * 255 * 255

  for i in range(256):
    p = palettePixels[i % 16,i / 16]
    d = abs(p[0] - pixel[0]) + abs(p[1] - pixel[1]) + abs(p[2] - pixel[2])

    if d < closestDist:
      result = i
      closestDist = d

    if d == 0:
      break

  return result

image = Image.open(sys.argv[1])
pixels = image.load()

pal = Image.open(sys.argv[2])
palPixels = pal.load()

outImage = Image.new("RGB",(image.size[0],image.size[1]),"white")
outPixels = outImage.load()

sys.stdout.write("const unsigned char image[] =\n{  ")
sys.stdout.write(str(image.size[0]) + ", " + str(image.size[1]) + " // width, height")

count = 0

for x in range(image.size[0]):
  for y in range(image.size[1]):
    if count % 14 == 0:
      sys.stdout.write("\n  ");

    p = pixels[x,y]

    closest = findClosest(p,palPixels)

    sys.stdout.write(",0x{:02x}".format(closest))

    outPixels[x,y] = palPixels[closest % 16,closest / 16]

    count += 1

print("\n};")

outImage.save("out.png")