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93 lines
2.1 KiB
Python
93 lines
2.1 KiB
Python
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# The Python Imaging Library.
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# $Id$
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#
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# SGI image file handling
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#
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# See "The SGI Image File Format (Draft version 0.97)", Paul Haeberli.
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# <ftp://ftp.sgi.com/graphics/SGIIMAGESPEC>
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#
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# History:
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# 1995-09-10 fl Created
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#
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# Copyright (c) 2008 by Karsten Hiddemann.
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# Copyright (c) 1997 by Secret Labs AB.
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# Copyright (c) 1995 by Fredrik Lundh.
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#
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# See the README file for information on usage and redistribution.
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#
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__version__ = "0.2"
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import Image, ImageFile
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def i16(c):
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return ord(c[1]) + (ord(c[0])<<8)
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def i32(c):
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return ord(c[3]) + (ord(c[2])<<8) + (ord(c[1])<<16) + (ord(c[0])<<24)
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def _accept(prefix):
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return i16(prefix) == 474
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##
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# Image plugin for SGI images.
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class SgiImageFile(ImageFile.ImageFile):
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format = "SGI"
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format_description = "SGI Image File Format"
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def _open(self):
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# HEAD
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s = self.fp.read(512)
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if i16(s) != 474:
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raise SyntaxError("not an SGI image file")
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# relevant header entries
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compression = ord(s[2])
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# bytes, dimension, zsize
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layout = ord(s[3]), i16(s[4:]), i16(s[10:])
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# determine mode from bytes/zsize
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if layout == (1, 2, 1) or layout == (1, 1, 1):
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self.mode = "L"
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elif layout == (1, 3, 3):
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self.mode = "RGB"
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elif layout == (1, 3, 4):
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self.mode = "RGBA"
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else:
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raise SyntaxError("unsupported SGI image mode")
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# size
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self.size = i16(s[6:]), i16(s[8:])
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# decoder info
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if compression == 0:
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offset = 512
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pagesize = self.size[0]*self.size[1]*layout[0]
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self.tile = []
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for layer in self.mode:
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self.tile.append(("raw", (0,0)+self.size, offset, (layer,0,-1)))
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offset = offset + pagesize
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elif compression == 1:
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self.tile = [("sgi_rle", (0,0)+self.size, 512, (self.mode, 0, -1))]
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#
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# registry
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Image.register_open("SGI", SgiImageFile, _accept)
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Image.register_extension("SGI", ".bw")
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Image.register_extension("SGI", ".rgb")
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Image.register_extension("SGI", ".rgba")
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Image.register_extension("SGI", ".sgi") # really?
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