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#
# The Python Imaging Library.
# $Id$
#
# SGI image file handling
#
# See "The SGI Image File Format (Draft version 0.97)", Paul Haeberli.
# <ftp://ftp.sgi.com/graphics/SGIIMAGESPEC>
#
# History:
# 1995-09-10 fl Created
#
# Copyright (c) 2008 by Karsten Hiddemann.
# Copyright (c) 1997 by Secret Labs AB.
# Copyright (c) 1995 by Fredrik Lundh.
#
# See the README file for information on usage and redistribution.
#
from PIL import Image, ImageFile, _binary
__version__ = "0.2"
i8 = _binary.i8
i16 = _binary.i16be
def _accept(prefix):
return len(prefix) >= 2 and i16(prefix) == 474
##
# Image plugin for SGI images.
class SgiImageFile(ImageFile.ImageFile):
format = "SGI"
format_description = "SGI Image File Format"
def _open(self):
# HEAD
s = self.fp.read(512)
if i16(s) != 474:
raise ValueError("Not an SGI image file")
# relevant header entries
compression = i8(s[2])
# bytes, dimension, zsize
layout = i8(s[3]), i16(s[4:]), i16(s[10:])
# determine mode from bytes/zsize
if layout == (1, 2, 1) or layout == (1, 1, 1):
self.mode = "L"
elif layout == (1, 3, 3):
self.mode = "RGB"
elif layout == (1, 3, 4):
self.mode = "RGBA"
else:
raise ValueError("Unsupported SGI image mode")
# size
self.size = i16(s[6:]), i16(s[8:])
# decoder info
if compression == 0:
offset = 512
pagesize = self.size[0]*self.size[1]*layout[0]
self.tile = []
for layer in self.mode:
self.tile.append(
("raw", (0, 0)+self.size, offset, (layer, 0, -1)))
offset = offset + pagesize
elif compression == 1:
raise ValueError("SGI RLE encoding not supported")
#
# registry
Image.register_open(SgiImageFile.format, SgiImageFile, _accept)
Image.register_extension(SgiImageFile.format, ".bw")
Image.register_extension(SgiImageFile.format, ".rgb")
Image.register_extension(SgiImageFile.format, ".rgba")
Image.register_extension(SgiImageFile.format, ".sgi")
# End of file
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