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88 lines
2.1 KiB
Python
88 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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from PIL import Image, ImageFile, _binary
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__version__ = "0.2"
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i8 = _binary.i8
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i16 = _binary.i16be
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def _accept(prefix):
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return len(prefix) >= 2 and 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 ValueError("Not an SGI image file")
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# relevant header entries
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compression = i8(s[2])
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# bytes, dimension, zsize
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layout = i8(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 ValueError("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(
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("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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raise ValueError("SGI RLE encoding not supported")
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#
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# registry
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Image.register_open(SgiImageFile.format, SgiImageFile, _accept)
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Image.register_extension(SgiImageFile.format, ".bw")
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Image.register_extension(SgiImageFile.format, ".rgb")
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Image.register_extension(SgiImageFile.format, ".rgba")
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Image.register_extension(SgiImageFile.format, ".sgi")
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