palfix.py outputs 2-bit grayscale if possible

This commit is contained in:
Rangi 2021-03-15 18:21:33 -04:00
parent ee36bd9342
commit 52bcd78290

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@ -12,7 +12,7 @@ def rgb8_to_rgb5(c):
def rgb5_to_rgb8(c): def rgb5_to_rgb8(c):
r, g, b = c r, g, b = c
return ((r * 8) | (r // 4), (g * 8) | (g // 4), (b * 8) | (b // 4)) return (r * 8 + r // 4, g * 8 + g // 4, b * 8 + b // 4)
def invert(c): def invert(c):
r, g, b = c r, g, b = c
@ -20,7 +20,7 @@ def invert(c):
def luminance(c): def luminance(c):
r, g, b = c r, g, b = c
return (0.299 * r**2 + 0.587 * g**2 + 0.114 * b**2)**0.5 return 0.299 * r**2 + 0.587 * g**2 + 0.114 * b**2
def rgb5_pixels(row): def rgb5_pixels(row):
for x in range(0, len(row), 4): for x in range(0, len(row), 4):
@ -33,7 +33,7 @@ def fix_pal(filename):
b_and_w = {(0, 0, 0), (31, 31, 31)} b_and_w = {(0, 0, 0), (31, 31, 31)}
colors = set(c for row in data for c in rgb5_pixels(row)) - b_and_w colors = set(c for row in data for c in rgb5_pixels(row)) - b_and_w
if not colors: if not colors:
colors = {(20, 20, 20), (10, 10, 10)} colors = {(21, 21, 21), (10, 10, 10)}
elif len(colors) == 1: elif len(colors) == 1:
c = colors.pop() c = colors.pop()
colors = {c, invert(c)} colors = {c, invert(c)}
@ -42,8 +42,12 @@ def fix_pal(filename):
palette = tuple(sorted(colors | b_and_w, key=luminance, reverse=True)) palette = tuple(sorted(colors | b_and_w, key=luminance, reverse=True))
assert len(palette) == 4 assert len(palette) == 4
data = [list(map(palette.index, rgb5_pixels(row))) for row in data] data = [list(map(palette.index, rgb5_pixels(row))) for row in data]
if palette == ((31, 31, 31), (21, 21, 21), (10, 10, 10), (0, 0, 0)):
data = [[3 - c for c in row] for row in data]
writer = png.Writer(width, height, greyscale=True, bitdepth=2, compression=9)
else:
palette = tuple(map(rgb5_to_rgb8, palette)) palette = tuple(map(rgb5_to_rgb8, palette))
writer = png.Writer(width, height, palette=palette, compression=9) writer = png.Writer(width, height, palette=palette, bitdepth=8, compression=9)
with open(filename, 'wb') as file: with open(filename, 'wb') as file:
writer.write(file, data) writer.write(file, data)
return True return True