Update and add more tool scripts

tools/palfix.py

@@ -0,0 +1,77 @@
+#!/usr/bin/env python3
+# -*- coding: utf-8 -*-
+
+"""
+Usage: python palfix.py image.png
+
+Fix the palette format of the input image. Colored images (Gen 2 Pokémon or
+trainer sprites) will become indexed, with a palette sorted {white, light
+color, dark color, black}. Grayscale images (all Gen 1 images) will become
+two-bit grayscale.
+"""
+
+import sys
+
+import png
+
+def rgb8_to_rgb5(c):
+	r, g, b = c
+	return (r // 8, g // 8, b // 8)
+
+def rgb5_to_rgb8(c):
+	r, g, b = c
+	return (r * 8 + r // 4, g * 8 + g // 4, b * 8 + b // 4)
+
+def invert(c):
+	r, g, b = c
+	return (31 - r, 31 - g, 31 - b)
+
+def luminance(c):
+	r, g, b = c
+	return 0.299 * r**2 + 0.587 * g**2 + 0.114 * b**2
+
+def rgb5_pixels(row):
+	yield from (rgb8_to_rgb5(row[x:x+3]) for x in range(0, len(row), 4))
+
+def is_grayscale(palette):
+	return (palette == ((31, 31, 31), (21, 21, 21), (10, 10, 10), (0, 0, 0)) or
+		palette == ((31, 31, 31), (20, 20, 20), (10, 10, 10), (0, 0, 0)))
+
+def fix_pal(filename):
+	with open(filename, 'rb') as file:
+		width, height, rows = png.Reader(file).asRGBA8()[:3]
+		rows = list(rows)
+	b_and_w = {(0, 0, 0), (31, 31, 31)}
+	colors = {c for row in rows for c in rgb5_pixels(row)} - b_and_w
+	if not colors:
+		colors = {(21, 21, 21), (10, 10, 10)}
+	elif len(colors) == 1:
+		c = colors.pop()
+		colors = {c, invert(c)}
+	elif len(colors) != 2:
+		return False
+	palette = tuple(sorted(colors | b_and_w, key=luminance, reverse=True))
+	assert len(palette) == 4
+	rows = [list(map(palette.index, rgb5_pixels(row))) for row in rows]
+	if is_grayscale(palette):
+		rows = [[3 - c for c in row] for row in rows]
+		writer = png.Writer(width, height, greyscale=True, bitdepth=2, compression=9)
+	else:
+		palette = tuple(map(rgb5_to_rgb8, palette))
+		writer = png.Writer(width, height, palette=palette, bitdepth=8, compression=9)
+	with open(filename, 'wb') as file:
+		writer.write(file, rows)
+	return True
+
+def main():
+	if len(sys.argv) < 2:
+		print(f'Usage: {sys.argv[0]} pic.png', file=sys.stderr)
+		sys.exit(1)
+	for filename in sys.argv[1:]:
+		if not filename.lower().endswith('.png'):
+			print(f'{filename} is not a .png file!', file=sys.stderr)
+		elif not fix_pal(filename):
+			print(f'{filename} has too many colors!', file=sys.stderr)
+
+if __name__ == '__main__':
+	main()