230 lines
5.9 KiB
Python
230 lines
5.9 KiB
Python
#
|
|
# 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.
|
|
#
|
|
|
|
|
|
import os
|
|
import struct
|
|
|
|
from . import Image, ImageFile
|
|
from ._binary import i16be as i16
|
|
from ._binary import o8
|
|
|
|
|
|
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.
|
|
class SgiImageFile(ImageFile.ImageFile):
|
|
|
|
format = "SGI"
|
|
format_description = "SGI Image File Format"
|
|
|
|
def _open(self):
|
|
|
|
# HEAD
|
|
headlen = 512
|
|
s = self.fp.read(headlen)
|
|
|
|
if not _accept(s):
|
|
raise ValueError("Not an SGI image file")
|
|
|
|
# compression : verbatim or RLE
|
|
compression = s[2]
|
|
|
|
# bpc : 1 or 2 bytes (8bits or 16bits)
|
|
bpc = 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]
|
|
if self.mode == "RGB":
|
|
self.custom_mimetype = "image/rgb"
|
|
|
|
# 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(
|
|
f"incorrect number of bands in SGI write: {z} vs {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]
|
|
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()
|
|
|
|
|
|
class SGI16Decoder(ImageFile.PyDecoder):
|
|
_pulls_fd = True
|
|
|
|
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_extensions(SgiImageFile.format, [".bw", ".rgb", ".rgba", ".sgi"])
|
|
|
|
# End of file
|