Source code for PIL.SgiImagePlugin

#
# 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:
# 2017-22-07 mb   Add RLE decompression
# 2016-16-10 mb   Add save method without compression
# 1995-09-10 fl   Created
#
# Copyright (c) 2016 by Mickael Bonfill.
# 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.
#


from . import Image, ImageFile
from ._binary import i8, o8, i16be as i16
from ._util import py3
import struct
import os


__version__ = "0.3"


def _accept(prefix):
    return len(prefix) >= 2 and i16(prefix) == 474


MODES = {
    (1, 1, 1): "L",
    (1, 2, 1): "L",
    (2, 1, 1): "L;16B",
    (2, 2, 1): "L;16B",
    (1, 3, 3): "RGB",
    (2, 3, 3): "RGB;16B",
    (1, 3, 4): "RGBA",
    (2, 3, 4): "RGBA;16B"
}


##
# Image plugin for SGI images.
[docs]class SgiImageFile(ImageFile.ImageFile): format = "SGI" format_description = "SGI Image File Format" def _open(self): # HEAD headlen = 512 s = self.fp.read(headlen) # magic number : 474 if i16(s) != 474: raise ValueError("Not an SGI image file") # compression : verbatim or RLE compression = i8(s[2]) # bpc : 1 or 2 bytes (8bits or 16bits) bpc = i8(s[3]) # dimension : 1, 2 or 3 (depending on xsize, ysize and zsize) dimension = i16(s[4:]) # xsize : width xsize = i16(s[6:]) # ysize : height ysize = i16(s[8:]) # zsize : channels count zsize = i16(s[10:]) # layout layout = bpc, dimension, zsize # determine mode from bits/zsize rawmode = "" try: rawmode = MODES[layout] except KeyError: pass if rawmode == "": raise ValueError("Unsupported SGI image mode") self._size = xsize, ysize self.mode = rawmode.split(";")[0] # orientation -1 : scanlines begins at the bottom-left corner orientation = -1 # decoder info if compression == 0: pagesize = xsize * ysize * bpc if bpc == 2: self.tile = [("SGI16", (0, 0) + self.size, headlen, (self.mode, 0, orientation))] else: self.tile = [] offset = headlen for layer in self.mode: self.tile.append( ("raw", (0, 0) + self.size, offset, (layer, 0, orientation))) offset += pagesize elif compression == 1: self.tile = [("sgi_rle", (0, 0) + self.size, headlen, (rawmode, orientation, bpc))]
def _save(im, fp, filename): if im.mode != "RGB" and im.mode != "RGBA" and im.mode != "L": raise ValueError("Unsupported SGI image mode") # Get the keyword arguments info = im.encoderinfo # Byte-per-pixel precision, 1 = 8bits per pixel bpc = info.get("bpc", 1) if bpc not in (1, 2): raise ValueError("Unsupported number of bytes per pixel") # Flip the image, since the origin of SGI file is the bottom-left corner orientation = -1 # Define the file as SGI File Format magicNumber = 474 # Run-Length Encoding Compression - Unsupported at this time rle = 0 # Number of dimensions (x,y,z) dim = 3 # X Dimension = width / Y Dimension = height x, y = im.size if im.mode == "L" and y == 1: dim = 1 elif im.mode == "L": dim = 2 # Z Dimension: Number of channels z = len(im.mode) if dim == 1 or dim == 2: z = 1 # assert we've got the right number of bands. if len(im.getbands()) != z: raise ValueError("incorrect number of bands in SGI write: %s vs %s" % (z, len(im.getbands()))) # Minimum Byte value pinmin = 0 # Maximum Byte value (255 = 8bits per pixel) pinmax = 255 # Image name (79 characters max, truncated below in write) imgName = os.path.splitext(os.path.basename(filename))[0] if py3: imgName = imgName.encode('ascii', 'ignore') # Standard representation of pixel in the file colormap = 0 fp.write(struct.pack('>h', magicNumber)) fp.write(o8(rle)) fp.write(o8(bpc)) fp.write(struct.pack('>H', dim)) fp.write(struct.pack('>H', x)) fp.write(struct.pack('>H', y)) fp.write(struct.pack('>H', z)) fp.write(struct.pack('>l', pinmin)) fp.write(struct.pack('>l', pinmax)) fp.write(struct.pack('4s', b'')) # dummy fp.write(struct.pack('79s', imgName)) # truncates to 79 chars fp.write(struct.pack('s', b'')) # force null byte after imgname fp.write(struct.pack('>l', colormap)) fp.write(struct.pack('404s', b'')) # dummy rawmode = 'L' if bpc == 2: rawmode = 'L;16B' for channel in im.split(): fp.write(channel.tobytes('raw', rawmode, 0, orientation)) fp.close()
[docs]class SGI16Decoder(ImageFile.PyDecoder): _pulls_fd = True
[docs] def decode(self, buffer): rawmode, stride, orientation = self.args pagesize = self.state.xsize * self.state.ysize zsize = len(self.mode) self.fd.seek(512) for band in range(zsize): channel = Image.new('L', (self.state.xsize, self.state.ysize)) channel.frombytes(self.fd.read(2 * pagesize), 'raw', 'L;16B', stride, orientation) self.im.putband(channel.im, band) return -1, 0
# # registry Image.register_decoder("SGI16", SGI16Decoder) Image.register_open(SgiImageFile.format, SgiImageFile, _accept) Image.register_save(SgiImageFile.format, _save) Image.register_mime(SgiImageFile.format, "image/sgi") Image.register_mime(SgiImageFile.format, "image/rgb") Image.register_extensions(SgiImageFile.format, [".bw", ".rgb", ".rgba", ".sgi"]) # End of file