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#!/usr/bin/env python
# pripalpng
# Convert to Palette PNG
from __future__ import print_function
import argparse
import collections
# https://docs.python.org/2.7/library/io.html
import io
import string
import struct
import sys
import warnings
import zlib
# Local module.
import png
def make_inverse_palette(rows, channels):
"""
The inverse palette maps from tuple to palette index.
"""
palette = {}
for row in rows:
for pixel in png.group(row, channels):
if pixel in palette:
continue
palette[pixel] = len(palette)
return palette
def palette_convert(inp, out, palette_file):
"""
Convert PNG image in `inp` to use a palette, colour type 3,
and write converted image to `out`.
`palette_file` is a file descriptor for the palette to use.
If `palette_file` is None, then `inp` is used as the palette.
"""
if palette_file is None:
inp, palette_file = palette_file, inp
reader = png.Reader(file=palette_file)
w, h, rows, info = asRGBorA8(reader)
channels = info["planes"]
if not inp:
rows = list(rows)
palette_map = make_inverse_palette(rows, channels)
if inp:
reader = png.Reader(file=inp)
w, h, rows, info = asRGBorA8(reader)
channels = info["planes"]
# Default for colours not in palette is to use last entry.
last = len(palette_map) - 1
def map_pixel(p):
return palette_map.get(p, last)
def convert_rows():
for row in rows:
yield [map_pixel(p) for p in png.group(row, channels)]
# Make a palette by sorting the pixels according to their index.
palette = sorted(palette_map.keys(), key=palette_map.get)
pal_info = dict(size=info["size"], palette=palette)
w = png.Writer(**pal_info)
w.write(out, convert_rows())
def asRGBorA8(reader):
"""
Return (width, height, rows, info) converting to RGB,
or RGBA if original has an alpha channel.
"""
_, _, _, info = reader.read()
if info["alpha"]:
return reader.asRGBA8()
else:
return reader.asRGB8()
def main(argv=None):
import re
if argv is None:
argv = sys.argv
argv = argv[1:]
parser = argparse.ArgumentParser()
parser.add_argument("--palette", type=argparse.FileType("rb"))
parser.add_argument("input", type=argparse.FileType("rb"))
args = parser.parse_args(argv)
# Fix for binary stdin on Python 3
try:
args.input = args.input.buffer
except AttributeError:
pass
# Fix for binary stdin on Python 3
try:
args.palette = args.palette.buffer
except AttributeError:
pass
palette_convert(args.input, png.binary_stdout(), args.palette)
if __name__ == "__main__":
main()
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