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161 lines
4.4 KiB
Python
161 lines
4.4 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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#
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# History:
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# 2016-16-10 mb Add save method without compression
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# 1995-09-10 fl Created
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#
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# Copyright (c) 2016 by Mickael Bonfill.
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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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import struct
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import os
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__version__ = "0.3"
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i8 = _binary.i8
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o8 = _binary.o8
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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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def _save(im, fp, filename):
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if im.mode != "RGB" and im.mode != "RGBA" and im.mode != "L":
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raise ValueError("Unsupported SGI image mode")
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# Flip the image, since the origin of SGI file is the bottom-left corner
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im = im.transpose(Image.FLIP_TOP_BOTTOM)
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# Define the file as SGI File Format
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magicNumber = 474
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# Run-Length Encoding Compression - Unsupported at this time
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rle = 0
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# Byte-per-pixel precision, 1 = 8bits per pixel
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bpc = 1
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# Number of dimensions (x,y,z)
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dim = 3
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# X Dimension = width / Y Dimension = height
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x, y = im.size
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if im.mode == "L" and y == 1:
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dim = 1
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elif im.mode == "L":
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dim = 2
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# Z Dimension: Number of channels
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z = len(im.mode)
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if dim == 1 or dim == 2:
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z = 1
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# Minimum Byte value
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pinmin = 0
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# Maximum Byte value (255 = 8bits per pixel)
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pinmax = 255
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# Image name (79 characters max, truncated below in write)
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imgName = os.path.splitext(os.path.basename(filename))[0]
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if str is not bytes:
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imgName = imgName.encode('ascii', 'ignore')
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# Standard representation of pixel in the file
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colormap = 0
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fp.write(struct.pack('>h', magicNumber))
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fp.write(o8(rle))
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fp.write(o8(bpc))
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fp.write(struct.pack('>H', dim))
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fp.write(struct.pack('>H', x))
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fp.write(struct.pack('>H', y))
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fp.write(struct.pack('>H', z))
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fp.write(struct.pack('>l', pinmin))
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fp.write(struct.pack('>l', pinmax))
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fp.write(struct.pack('4s', b'')) # dummy
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fp.write(struct.pack('79s', imgName)) # truncates to 79 chars
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fp.write(struct.pack('s', b'')) # force null byte after imgname
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fp.write(struct.pack('>l', colormap))
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fp.write(struct.pack('404s', b'')) # dummy
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#assert we've got the right number of bands.
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if len(im.getbands()) != z:
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raise ValueError("incorrect number of bands in SGI write: %s vs %s" %
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(z, len(im.getbands())))
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for channel in im.split():
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fp.write(channel.tobytes())
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fp.close()
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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_save(SgiImageFile.format, _save)
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Image.register_mime(SgiImageFile.format, "image/sgi")
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Image.register_mime(SgiImageFile.format, "image/rgb")
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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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# End of file
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