#
|
# 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?
|
