#
# 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.
#
__version__ = "0.2"
import Image, ImageFile
def i16(c):
return ord(c[1]) + (ord(c[0])<<8)
def i32(c):
return ord(c[3]) + (ord(c[2])<<8) + (ord(c[1])<<16) + (ord(c[0])<<24)
def _accept(prefix):
return 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 SyntaxError("not an SGI image file")
# relevant header entries
compression = ord(s[2])
# bytes, dimension, zsize
layout = ord(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 SyntaxError("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:
self.tile = [("sgi_rle", (0,0)+self.size, 512, (self.mode, 0, -1))]
#
# registry
Image.register_open("SGI", SgiImageFile, _accept)
Image.register_extension("SGI", ".bw")
Image.register_extension("SGI", ".rgb")
Image.register_extension("SGI", ".rgba")
Image.register_extension("SGI", ".sgi") # really?
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