Created
November 2, 2017 22:50
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PPM to PBM to PNG
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from PIL import Image | |
from io import BytesIO | |
import itertools | |
def as_pbm(w, h, data): # -> bytes | |
ret = bytes() | |
ret += b'P4\n' | |
ret += (str(w) + ' ' + str(h) + '\n').encode('ascii') | |
ret += plain_to_binary(data) | |
return ret | |
def read_pbm(data): | |
return ''.join(format(x, '08b') for x in data) | |
def plain_to_binary(data): # -> bytes | |
lines = (d.replace(' ', '') for d in data.strip().split('\n')) | |
ints = itertools.chain.from_iterable(bits_to_bytes(l) for l in lines) | |
return b''.join(int_to_bytes(i) for i in ints) | |
def bits_to_bytes(bits): | |
padded_bytes = itertools.zip_longest(*(iter(bits),) * 8, fillvalue='0') | |
padded_bytes = ([str.join('', z) for z in padded_bytes]) | |
return [int(byte, 2) for byte in padded_bytes] | |
def int_to_bytes(i): | |
return i.to_bytes((i.bit_length() + 7) // 8, 'big') or b'\0' | |
def as_png(w, h, data): # -> bytes | |
pbm_bytes = as_pbm(w, h, data) | |
infile = BytesIO(pbm_bytes) | |
outfile = BytesIO() | |
img = Image.open(infile) | |
img.save(outfile, 'PNG') | |
return outfile.getvalue() | |
data = ''' | |
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 | |
0 1 1 1 1 0 0 1 1 1 1 0 0 1 1 1 1 0 0 1 1 1 1 0 | |
0 1 0 0 0 0 0 1 0 0 0 0 0 1 0 0 0 0 0 1 0 0 1 0 | |
0 1 1 1 0 0 0 1 1 1 0 0 0 1 1 1 0 0 0 1 1 1 1 0 | |
0 1 0 0 0 0 0 1 0 0 0 0 0 1 0 0 0 0 0 1 0 0 0 0 | |
0 1 0 0 0 0 0 1 1 1 1 0 0 1 1 1 1 0 0 1 0 0 0 0 | |
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0''' | |
assert read_pbm(plain_to_binary(data)) == data.replace('\n', '').replace(' ', '') | |
open('test.png', 'wb').write(as_png(24, 7, data)) |
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