#
# The Python Imaging Library.
# $Id$
#
# PPM support for PIL
#
# History:
# 96-03-24 fl Created
# 98-03-06 fl Write RGBA images (as RGB, that is)
#
# Copyright (c) Secret Labs AB 1997-98.
# Copyright (c) Fredrik Lundh 1996.
#
# See the README file for information on usage and redistribution.
#
import string
from PIL import Image, ImageFile
__version__ = "0.2"
#
# --------------------------------------------------------------------
b_whitespace = string.whitespace
try:
import locale
locale_lang, locale_enc = locale.getlocale()
if locale_enc is None:
locale_lang, locale_enc = locale.getdefaultlocale()
b_whitespace = b_whitespace.decode(locale_enc)
except:
pass
b_whitespace = b_whitespace.encode('ascii', 'ignore')
MODES = {
# standard
b"P4": "1",
b"P5": "L",
b"P6": "RGB",
# extensions
b"P0CMYK": "CMYK",
# PIL extensions (for test purposes only)
b"PyP": "P",
b"PyRGBA": "RGBA",
b"PyCMYK": "CMYK"
}
def _accept(prefix):
return prefix[0:1] == b"P" and prefix[1] in b"0456y"
##
# Image plugin for PBM, PGM, and PPM images.
[文档]class PpmImageFile(ImageFile.ImageFile):
format = "PPM"
format_description = "Pbmplus image"
def _token(self, s=b""):
while True: # read until next whitespace
c = self.fp.read(1)
if not c or c in b_whitespace:
break
if c > b'\x79':
raise ValueError("Expected ASCII value, found binary")
s = s + c
if (len(s) > 9):
raise ValueError("Expected int, got > 9 digits")
return s
def _open(self):
# check magic
s = self.fp.read(1)
if s != b"P":
raise SyntaxError("not a PPM file")
mode = MODES[self._token(s)]
if mode == "1":
self.mode = "1"
rawmode = "1;I"
else:
self.mode = rawmode = mode
for ix in range(3):
while True:
while True:
s = self.fp.read(1)
if s not in b_whitespace:
break
if s == b"":
raise ValueError("File does not extend beyond magic number")
if s != b"#":
break
s = self.fp.readline()
s = int(self._token(s))
if ix == 0:
xsize = s
elif ix == 1:
ysize = s
if mode == "1":
break
elif ix == 2:
# maxgrey
if s > 255:
if not mode == 'L':
raise ValueError("Too many colors for band: %s" % s)
if s < 2**16:
self.mode = 'I'
rawmode = 'I;16B'
else:
self.mode = 'I'
rawmode = 'I;32B'
self.size = xsize, ysize
self.tile = [("raw",
(0, 0, xsize, ysize),
self.fp.tell(),
(rawmode, 0, 1))]
# ALTERNATIVE: load via builtin debug function
# self.im = Image.core.open_ppm(self.filename)
# self.mode = self.im.mode
# self.size = self.im.size
#
# --------------------------------------------------------------------
def _save(im, fp, filename):
if im.mode == "1":
rawmode, head = "1;I", b"P4"
elif im.mode == "L":
rawmode, head = "L", b"P5"
elif im.mode == "I":
if im.getextrema()[1] < 2**16:
rawmode, head = "I;16B", b"P5"
else:
rawmode, head = "I;32B", b"P5"
elif im.mode == "RGB":
rawmode, head = "RGB", b"P6"
elif im.mode == "RGBA":
rawmode, head = "RGB", b"P6"
else:
raise IOError("cannot write mode %s as PPM" % im.mode)
fp.write(head + ("\n%d %d\n" % im.size).encode('ascii'))
if head == b"P6":
fp.write(b"255\n")
if head == b"P5":
if rawmode == "L":
fp.write(b"255\n")
elif rawmode == "I;16B":
fp.write(b"65535\n")
elif rawmode == "I;32B":
fp.write(b"2147483648\n")
ImageFile._save(im, fp, [("raw", (0, 0)+im.size, 0, (rawmode, 0, 1))])
# ALTERNATIVE: save via builtin debug function
# im._dump(filename)
#
# --------------------------------------------------------------------
Image.register_open(PpmImageFile.format, PpmImageFile, _accept)
Image.register_save(PpmImageFile.format, _save)
Image.register_extension(PpmImageFile.format, ".pbm")
Image.register_extension(PpmImageFile.format, ".pgm")
Image.register_extension(PpmImageFile.format, ".ppm")