Spritesheet cutter

Yesterday in our SPb Python telegram chat a question "how to automatically cut spritesheet into several sprites" was asked. An example of spritesheet image is here: http://www.spriters-resource.com/3ds/animalcrossinghappyhomedesigner/sheet/68350/
Several solutions were proposed, and today I've decided to write my own solution.

So the problem is to cut each sprite out and save to separate file. As a parameter could be passed the color of border. By the way by default it could be fetched from top left pixel. I've coded a Python script that takes input spritesheet image, border color if known, and output folder to save found and cutted out sprites. Output sprite images are grouped by size.

	#!/usr/bin/env python
	#-*- coding: utf-8 -*-
	#-----------------------------------------------------------------------
	# Author: delimitry
	#-----------------------------------------------------------------------
	import os
	import sys
	from PIL import Image
	from argparse import ArgumentParser
	def find_horizontal_borders(image, border_color):
	"""
	Find horizontal border lines with defined color
	"""
	w, h = image.size
	pixels = image.load()
	horizontals = []
	for j in xrange(h):
	for i in xrange(w):
	if pixels[i, j] != border_color:
	break
	else:
	horizontals.append(j)
	return horizontals
	def find_vertial_borders(image, border_color):
	"""
	Find vertical border lines with defined color
	"""
	w, h = image.size
	pixels = image.load()
	verticals = []
	for i in xrange(w):
	for j in xrange(h):
	if pixels[i, j] != border_color:
	break
	else:
	verticals.append(i)
	return verticals
	def find_areas(image, border_color):
	"""
	Find sprite areas and return a list of rectangles (x, y, w, h).
	"""
	w, h = image.size
	horizontals = find_horizontal_borders(image, border_color)
	areas = []
	prev_horizontal = 0
	for h in horizontals:
	if h - prev_horizontal > 1:
	verticals = find_vertial_borders(
	image.crop((0, prev_horizontal + 1, w, prev_horizontal + (h - prev_horizontal))), border_color)
	prev_vertical = 0
	for v in verticals:
	if v - prev_vertical > 1:
	areas.append(
	(prev_vertical + 1, prev_horizontal + 1, v - prev_vertical - 1, h - prev_horizontal - 1))
	prev_vertical = v
	prev_horizontal = h
	return areas
	def str_to_color(value):
	"""
	Convert str value to color (tuple of ints)
	"""
	try:
	if ',' not in value or value.count(',') not in (2, 3):
	raise
	color = tuple([int(x) for x in value.split(',')])
	for c in color:
	if not 0 <= c <= 255:
	raise
	return color
	except:
	raise Exception('Invalid format of color. Must be (R,G,B) or (R,G,B,A), '
	'where RGBA channels must be in [0..255]')
	def cut_and_save_sprites(image, areas, output_folder):
	"""
	Cut sprites from image using found areas and save to output folder, grouping them by size
	"""
	if not os.path.exists(output_folder):
	os.makedirs(output_folder)
	if not areas:
	return
	group = 0
	index = 0
	# get [w, h] from first area (x, y, w, h)
	prev_size = areas[0][2:4]
	for area in areas:
	# assume that a new group starts when a new size is found
	if area[2:4] != prev_size:
	prev_size = area[2:4]
	group += 1
	index = 0
	image.crop((area[0], area[1], area[0] + area[2] - 0, area[1] + area[3] - 0)).save(
	os.path.join(output_folder, 'group_%02d_index_%03d.png' % (group, index)))
	index += 1
	def main():
	# prepare arguments parser
	parser = ArgumentParser(usage='%(prog)s [options]', description='Spritesheet image cutter')
	parser.add_argument('-i', '--input', dest='input', help='spritesheet image')
	parser.add_argument('-c', '--color', dest='color',
	help='border RGB/RGBA color (e.g.: 255,0,128 or 0,0,0,255), by default color of top left pixel', default='')
	parser.add_argument('-o', '--output', dest='output',
	help='output sprites folder, by default current folder', default='./')
	parser.add_argument('-v', '--version', action='version', version='Spritesheet image cutter v0.1')
	args = parser.parse_args()
	if not args.input:
	parser.print_help()
	sys.exit()
	image = Image.open(args.input)
	left_top_color = image.getpixel((0, 0))
	if args.color:
	try:
	border_color = str_to_color(args.color)
	except Exception as ex:
	sys.exit(ex)
	else:
	# get top left pixel color if not color passed
	border_color = left_top_color
	# check color channels
	if len(border_color) != len(left_top_color):
	print 'Warning: Image color channels number is %d, but you have passed %d.' % (
	len(left_top_color), len(border_color))
	sys.exit()
	areas = find_areas(image, border_color)
	if not areas:
	print 'No sprites were found.'
	sys.exit()
	print 'Saving %s sprites to "%s"' % (len(areas), os.path.abspath(args.output))
	cut_and_save_sprites(image, areas, args.output)
	if __name__ == '__main__':
	main()

view raw spritesheet_cutter.py hosted with ❤ by GitHub