Web   ·   Wiki   ·   Activities   ·   Blog   ·   Lists   ·   Chat   ·   Meeting   ·   Bugs   ·   Git   ·   Translate   ·   Archive   ·   People   ·   Donate
summaryrefslogtreecommitdiffstats
path: root/PIL/TiffImagePlugin.py
blob: 178066c8f02add1db98ba2c40d7170f001f622d4 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
#
# The Python Imaging Library.
# $Id: TiffImagePlugin.py 2803 2006-07-31 19:18:57Z fredrik $
#
# TIFF file handling
#
# TIFF is a flexible, if somewhat aged, image file format originally
# defined by Aldus.  Although TIFF supports a wide variety of pixel
# layouts and compression methods, the name doesn't really stand for
# "thousands of incompatible file formats," it just feels that way.
#
# To read TIFF data from a stream, the stream must be seekable.  For
# progressive decoding, make sure to use TIFF files where the tag
# directory is placed first in the file.
#
# History:
# 1995-09-01 fl   Created
# 1996-05-04 fl   Handle JPEGTABLES tag
# 1996-05-18 fl   Fixed COLORMAP support
# 1997-01-05 fl   Fixed PREDICTOR support
# 1997-08-27 fl   Added support for rational tags (from Perry Stoll)
# 1998-01-10 fl   Fixed seek/tell (from Jan Blom)
# 1998-07-15 fl   Use private names for internal variables
# 1999-06-13 fl   Rewritten for PIL 1.0 (1.0)
# 2000-10-11 fl   Additional fixes for Python 2.0 (1.1)
# 2001-04-17 fl   Fixed rewind support (seek to frame 0) (1.2)
# 2001-05-12 fl   Added write support for more tags (from Greg Couch) (1.3)
# 2001-12-18 fl   Added workaround for broken Matrox library
# 2002-01-18 fl   Don't mess up if photometric tag is missing (D. Alan Stewart)
# 2003-05-19 fl   Check FILLORDER tag
# 2003-09-26 fl   Added RGBa support
# 2004-02-24 fl   Added DPI support; fixed rational write support
# 2005-02-07 fl   Added workaround for broken Corel Draw 10 files
# 2006-01-09 fl   Added support for float/double tags (from Russell Nelson)
#
# Copyright (c) 1997-2006 by Secret Labs AB.  All rights reserved.
# Copyright (c) 1995-1997 by Fredrik Lundh
#
# See the README file for information on usage and redistribution.
#

__version__ = "1.3.5"

import Image, ImageFile
import ImagePalette

import array, string, sys

try:
    if sys.byteorder == "little":
        byteorder = "II"
    else:
        byteorder = "MM"
except AttributeError:
    if ord(array.array("i",[1]).tostring()[0]):
        byteorder = "II"
    else:
        byteorder = "MM"

#
# --------------------------------------------------------------------
# Read TIFF files

def il16(c,o=0):
    return ord(c[o]) + (ord(c[o+1])<<8)
def il32(c,o=0):
    return ord(c[o]) + (ord(c[o+1])<<8) + (ord(c[o+2])<<16) + (ord(c[o+3])<<24)
def ol16(i):
    return chr(i&255) + chr(i>>8&255)
def ol32(i):
    return chr(i&255) + chr(i>>8&255) + chr(i>>16&255) + chr(i>>24&255)

def ib16(c,o=0):
    return ord(c[o+1]) + (ord(c[o])<<8)
def ib32(c,o=0):
    return ord(c[o+3]) + (ord(c[o+2])<<8) + (ord(c[o+1])<<16) + (ord(c[o])<<24)

# a few tag names, just to make the code below a bit more readable
IMAGEWIDTH = 256
IMAGELENGTH = 257
BITSPERSAMPLE = 258
COMPRESSION = 259
PHOTOMETRIC_INTERPRETATION = 262
FILLORDER = 266
IMAGEDESCRIPTION = 270
STRIPOFFSETS = 273
SAMPLESPERPIXEL = 277
ROWSPERSTRIP = 278
STRIPBYTECOUNTS = 279
X_RESOLUTION = 282
Y_RESOLUTION = 283
PLANAR_CONFIGURATION = 284
RESOLUTION_UNIT = 296
SOFTWARE = 305
DATE_TIME = 306
ARTIST = 315
PREDICTOR = 317
COLORMAP = 320
EXTRASAMPLES = 338
SAMPLEFORMAT = 339
JPEGTABLES = 347
COPYRIGHT = 33432
IPTC_NAA_CHUNK = 33723 # newsphoto properties
PHOTOSHOP_CHUNK = 34377 # photoshop properties

COMPRESSION_INFO = {
    # Compression => pil compression name
    1: "raw",
    2: "tiff_ccitt",
    3: "group3",
    4: "group4",
    5: "tiff_lzw",
    6: "tiff_jpeg", # obsolete
    7: "jpeg",
    32771: "tiff_raw_16", # 16-bit padding
    32773: "packbits"
}

OPEN_INFO = {
    # (PhotoInterpretation, SampleFormat, FillOrder, BitsPerSample,
    #  ExtraSamples) => mode, rawmode
    (0, 1, 1, (1,), ()): ("1", "1;I"),
    (0, 1, 2, (1,), ()): ("1", "1;IR"),
    (0, 1, 1, (8,), ()): ("L", "L;I"),
    (0, 1, 2, (8,), ()): ("L", "L;IR"),
    (1, 1, 1, (1,), ()): ("1", "1"),
    (1, 1, 2, (1,), ()): ("1", "1;R"),
    (1, 1, 1, (8,), ()): ("L", "L"),
    (1, 1, 1, (8,8), (2,)): ("LA", "LA"),
    (1, 1, 2, (8,), ()): ("L", "L;R"),
    (1, 1, 1, (16,), ()): ("I;16", "I;16"),
    (1, 2, 1, (16,), ()): ("I;16S", "I;16S"),
    (1, 2, 1, (32,), ()): ("I", "I;32S"),
    (1, 3, 1, (32,), ()): ("F", "F;32F"),
    (2, 1, 1, (8,8,8), ()): ("RGB", "RGB"),
    (2, 1, 2, (8,8,8), ()): ("RGB", "RGB;R"),
    (2, 1, 1, (8,8,8,8), (0,)): ("RGBX", "RGBX"),
    (2, 1, 1, (8,8,8,8), (1,)): ("RGBA", "RGBa"),
    (2, 1, 1, (8,8,8,8), (2,)): ("RGBA", "RGBA"),
    (2, 1, 1, (8,8,8,8), (999,)): ("RGBA", "RGBA"), # corel draw 10
    (3, 1, 1, (1,), ()): ("P", "P;1"),
    (3, 1, 2, (1,), ()): ("P", "P;1R"),
    (3, 1, 1, (2,), ()): ("P", "P;2"),
    (3, 1, 2, (2,), ()): ("P", "P;2R"),
    (3, 1, 1, (4,), ()): ("P", "P;4"),
    (3, 1, 2, (4,), ()): ("P", "P;4R"),
    (3, 1, 1, (8,), ()): ("P", "P"),
    (3, 1, 1, (8,8), (2,)): ("PA", "PA"),
    (3, 1, 2, (8,), ()): ("P", "P;R"),
    (5, 1, 1, (8,8,8,8), ()): ("CMYK", "CMYK"),
    (6, 1, 1, (8,8,8), ()): ("YCbCr", "YCbCr"),
    (8, 1, 1, (8,8,8), ()): ("LAB", "LAB"),
}

PREFIXES = ["MM\000\052", "II\052\000", "II\xBC\000"]

def _accept(prefix):
    return prefix[:4] in PREFIXES

##
# Wrapper for TIFF IFDs.

class ImageFileDirectory:

    # represents a TIFF tag directory.  to speed things up,
    # we don't decode tags unless they're asked for.

    def __init__(self, prefix="II"):
        self.prefix = prefix[:2]
        if self.prefix == "MM":
            self.i16, self.i32 = ib16, ib32
            # FIXME: save doesn't yet support big-endian mode...
        elif self.prefix == "II":
            self.i16, self.i32 = il16, il32
            self.o16, self.o32 = ol16, ol32
        else:
            raise SyntaxError("not a TIFF IFD")
        self.reset()

    def reset(self):
        self.tags = {}
        self.tagdata = {}
        self.next = None

    # dictionary API (sort of)

    def keys(self):
        return self.tagdata.keys() + self.tags.keys()

    def items(self):
        items = self.tags.items()
        for tag in self.tagdata.keys():
            items.append((tag, self[tag]))
        return items

    def __len__(self):
        return len(self.tagdata) + len(self.tags)

    def __getitem__(self, tag):
        try:
            return self.tags[tag]
        except KeyError:
            type, data = self.tagdata[tag] # unpack on the fly
            size, handler = self.load_dispatch[type]
            self.tags[tag] = data = handler(self, data)
            del self.tagdata[tag]
            return data

    def get(self, tag, default=None):
        try:
            return self[tag]
        except KeyError:
            return default

    def getscalar(self, tag, default=None):
        try:
            value = self[tag]
            if len(value) != 1:
                if tag == SAMPLEFORMAT:
                    # work around broken (?) matrox library
                    # (from Ted Wright, via Bob Klimek)
                    raise KeyError # use default
                raise ValueError, "not a scalar"
            return value[0]
        except KeyError:
            if default is None:
                raise
            return default

    def has_key(self, tag):
        return self.tags.has_key(tag) or self.tagdata.has_key(tag)

    def __setitem__(self, tag, value):
        if type(value) is not type(()):
            value = (value,)
        self.tags[tag] = value

    # load primitives

    load_dispatch = {}

    def load_byte(self, data):
        l = []
        for i in range(len(data)):
            l.append(ord(data[i]))
        return tuple(l)
    load_dispatch[1] = (1, load_byte)

    def load_string(self, data):
        if data[-1:] == '\0':
            data = data[:-1]
        return data
    load_dispatch[2] = (1, load_string)

    def load_short(self, data):
        l = []
        for i in range(0, len(data), 2):
            l.append(self.i16(data, i))
        return tuple(l)
    load_dispatch[3] = (2, load_short)

    def load_long(self, data):
        l = []
        for i in range(0, len(data), 4):
            l.append(self.i32(data, i))
        return tuple(l)
    load_dispatch[4] = (4, load_long)

    def load_rational(self, data):
        l = []
        for i in range(0, len(data), 8):
            l.append((self.i32(data, i), self.i32(data, i+4)))
        return tuple(l)
    load_dispatch[5] = (8, load_rational)

    def load_float(self, data):
        a = array.array("f", data)
        if self.prefix != byteorder:
            a.byteswap()
        return tuple(a)
    load_dispatch[11] = (4, load_float)

    def load_double(self, data):
        a = array.array("d", data)
        if self.prefix != byteorder:
            a.byteswap()
        return tuple(a)
    load_dispatch[12] = (8, load_double)

    def load_undefined(self, data):
        # Untyped data
        return data
    load_dispatch[7] = (1, load_undefined)

    def load(self, fp):
        # load tag dictionary

        self.reset()

        i16 = self.i16
        i32 = self.i32

        for i in range(i16(fp.read(2))):

            ifd = fp.read(12)

            tag, typ = i16(ifd), i16(ifd, 2)

            if Image.DEBUG:
                import TiffTags
                tagname = TiffTags.TAGS.get(tag, "unknown")
                typname = TiffTags.TYPES.get(typ, "unknown")
                print "tag: %s (%d)" % (tagname, tag),
                print "- type: %s (%d)" % (typname, typ),

            try:
                dispatch = self.load_dispatch[typ]
            except KeyError:
                if Image.DEBUG:
                    print "- unsupported type", typ
                continue # ignore unsupported type

            size, handler = dispatch

            size = size * i32(ifd, 4)

            # Get and expand tag value
            if size > 4:
                here = fp.tell()
                fp.seek(i32(ifd, 8))
                data = ImageFile._safe_read(fp, size)
                fp.seek(here)
            else:
                data = ifd[8:8+size]

            if len(data) != size:
                raise IOError, "not enough data"

            self.tagdata[tag] = typ, data

            if Image.DEBUG:
                if tag in (COLORMAP, IPTC_NAA_CHUNK, PHOTOSHOP_CHUNK):
                    print "- value: <table: %d bytes>" % size
                else:
                    print "- value:", self[tag]

        self.next = i32(fp.read(4))

    # save primitives

    def save(self, fp):

        o16 = self.o16
        o32 = self.o32

        fp.write(o16(len(self.tags)))

        # always write in ascending tag order
        tags = self.tags.items()
        tags.sort()

        directory = []
        append = directory.append

        offset = fp.tell() + len(self.tags) * 12 + 4

        stripoffsets = None

        # pass 1: convert tags to binary format
        for tag, value in tags:

            if Image.DEBUG:
                import TiffTags
                tagname = TiffTags.TAGS.get(tag, "unknown")
                print "save: %s (%d)" % (tagname, tag),
                print "- value:", value

            if type(value[0]) is type(""):
                # string data
                typ = 2
                data = value = string.join(value, "\0") + "\0"

            else:
                # integer data
                if tag == STRIPOFFSETS:
                    stripoffsets = len(directory)
                    typ = 4 # to avoid catch-22
                elif tag in (X_RESOLUTION, Y_RESOLUTION):
                    # identify rational data fields
                    typ = 5
                else:
                    typ = 3
                    for v in value:
                        if v >= 65536:
                            typ = 4
                if typ == 3:
                    data = string.join(map(o16, value), "")
                else:
                    data = string.join(map(o32, value), "")

            # figure out if data fits into the directory
            if len(data) == 4:
                append((tag, typ, len(value), data, ""))
            elif len(data) < 4:
                append((tag, typ, len(value), data + (4-len(data))*"\0", ""))
            else:
                count = len(value)
                if typ == 5:
                    count = count / 2        # adjust for rational data field
                append((tag, typ, count, o32(offset), data))
                offset = offset + len(data)
                if offset & 1:
                    offset = offset + 1 # word padding

        # update strip offset data to point beyond auxiliary data
        if stripoffsets is not None:
            tag, typ, count, value, data = directory[stripoffsets]
            assert not data, "multistrip support not yet implemented"
            value = o32(self.i32(value) + offset)
            directory[stripoffsets] = tag, typ, count, value, data

        # pass 2: write directory to file
        for tag, typ, count, value, data in directory:
            if Image.DEBUG > 1:
                print tag, typ, count, repr(value), repr(data)
            fp.write(o16(tag) + o16(typ) + o32(count) + value)
        fp.write("\0\0\0\0") # end of directory

        # pass 3: write auxiliary data to file
        for tag, typ, count, value, data in directory:
            fp.write(data)
            if len(data) & 1:
                fp.write("\0")

        return offset

##
# Image plugin for TIFF files.

class TiffImageFile(ImageFile.ImageFile):

    format = "TIFF"
    format_description = "Adobe TIFF"

    def _open(self):
        "Open the first image in a TIFF file"

        # Header
        ifh = self.fp.read(8)

        if ifh[:4] not in PREFIXES:
            raise SyntaxError, "not a TIFF file"

        # image file directory (tag dictionary)
        self.tag = self.ifd = ImageFileDirectory(ifh[:2])

        # setup frame pointers
        self.__first = self.__next = self.ifd.i32(ifh, 4)
        self.__frame = -1
        self.__fp = self.fp

        # and load the first frame
        self._seek(0)

    def seek(self, frame):
        "Select a given frame as current image"

        if frame < 0:
            frame = 0
        self._seek(frame)

    def tell(self):
        "Return the current frame number"

        return self._tell()

    def _seek(self, frame):

        self.fp = self.__fp
        if frame < self.__frame:
            # rewind file
            self.__frame = -1
            self.__next = self.__first
        while self.__frame < frame:
            if not self.__next:
                raise EOFError, "no more images in TIFF file"
            self.fp.seek(self.__next)
            self.tag.load(self.fp)
            self.__next = self.tag.next
            self.__frame = self.__frame + 1
        self._setup()

    def _tell(self):

        return self.__frame

    def _decoder(self, rawmode, layer):
        "Setup decoder contexts"

        args = None
        if rawmode == "RGB" and self._planar_configuration == 2:
            rawmode = rawmode[layer]
        compression = self._compression
        if compression == "raw":
            args = (rawmode, 0, 1)
        elif compression == "jpeg":
            args = rawmode, ""
            if self.tag.has_key(JPEGTABLES):
                # Hack to handle abbreviated JPEG headers
                self.tile_prefix = self.tag[JPEGTABLES]
        elif compression == "packbits":
            args = rawmode
        elif compression == "tiff_lzw":
            args = rawmode
            if self.tag.has_key(317):
                # Section 14: Differencing Predictor
                self.decoderconfig = (self.tag[PREDICTOR][0],)

        return args

    def _setup(self):
        "Setup this image object based on current tags"

        if self.tag.has_key(0xBC01):
            raise IOError, "Windows Media Photo files not yet supported"

        getscalar = self.tag.getscalar

        # extract relevant tags
        self._compression = COMPRESSION_INFO[getscalar(COMPRESSION, 1)]
        self._planar_configuration = getscalar(PLANAR_CONFIGURATION, 1)

        # photometric is a required tag, but not everyone is reading
        # the specification
        photo = getscalar(PHOTOMETRIC_INTERPRETATION, 0)

        fillorder = getscalar(FILLORDER, 1)

        if Image.DEBUG:
            print "*** Summary ***"
            print "- compression:", self._compression
            print "- photometric_interpretation:", photo
            print "- planar_configuration:", self._planar_configuration
            print "- fill_order:", fillorder

        # size
        xsize = getscalar(IMAGEWIDTH)
        ysize = getscalar(IMAGELENGTH)
        self.size = xsize, ysize

        if Image.DEBUG:
            print "- size:", self.size

        format = getscalar(SAMPLEFORMAT, 1)

        # mode: check photometric interpretation and bits per pixel
        key = (
            photo, format, fillorder,
            self.tag.get(BITSPERSAMPLE, (1,)),
            self.tag.get(EXTRASAMPLES, ())
            )
        if Image.DEBUG:
            print "format key:", key
        try:
            self.mode, rawmode = OPEN_INFO[key]
        except KeyError:
            if Image.DEBUG:
                print "- unsupported format"
            raise SyntaxError, "unknown pixel mode"

        if Image.DEBUG:
            print "- raw mode:", rawmode
            print "- pil mode:", self.mode

        self.info["compression"] = self._compression

        xdpi = getscalar(X_RESOLUTION, (1, 1))
        ydpi = getscalar(Y_RESOLUTION, (1, 1))

        if xdpi and ydpi and getscalar(RESOLUTION_UNIT, 1) == 1:
            xdpi = xdpi[0] / (xdpi[1] or 1)
            ydpi = ydpi[0] / (ydpi[1] or 1)
            self.info["dpi"] = xdpi, ydpi

        # build tile descriptors
        x = y = l = 0
        self.tile = []
        if self.tag.has_key(STRIPOFFSETS):
            # striped image
            h = getscalar(ROWSPERSTRIP, ysize)
            w = self.size[0]
            a = None
            for o in self.tag[STRIPOFFSETS]:
                if not a:
                    a = self._decoder(rawmode, l)
                self.tile.append(
                    (self._compression,
                    (0, min(y, ysize), w, min(y+h, ysize)),
                    o, a))
                y = y + h
                if y >= self.size[1]:
                    x = y = 0
                    l = l + 1
                    a = None
        elif self.tag.has_key(324):
            # tiled image
            w = getscalar(322)
            h = getscalar(323)
            a = None
            for o in self.tag[324]:
                if not a:
                    a = self._decoder(rawmode, l)
                # FIXME: this doesn't work if the image size
                # is not a multiple of the tile size...
                self.tile.append(
                    (self._compression,
                    (x, y, x+w, y+h),
                    o, a))
                x = x + w
                if x >= self.size[0]:
                    x, y = 0, y + h
                    if y >= self.size[1]:
                        x = y = 0
                        l = l + 1
                        a = None
        else:
            if Image.DEBUG:
                print "- unsupported data organization"
            raise SyntaxError("unknown data organization")

        # fixup palette descriptor
        if self.mode == "P":
            palette = map(lambda a: chr(a / 256), self.tag[COLORMAP])
            self.palette = ImagePalette.raw("RGB;L", string.join(palette, ""))

#
# --------------------------------------------------------------------
# Write TIFF files

# little endian is default

SAVE_INFO = {
    # mode => rawmode, photometrics, sampleformat, bitspersample, extra
    "1": ("1", 1, 1, (1,), None),
    "L": ("L", 1, 1, (8,), None),
    "LA": ("LA", 1, 1, (8,8), 2),
    "P": ("P", 3, 1, (8,), None),
    "PA": ("PA", 3, 1, (8,8), 2),
    "I": ("I;32S", 1, 2, (32,), None),
    "I;16": ("I;16", 1, 1, (16,), None),
    "I;16S": ("I;16S", 1, 2, (16,), None),
    "F": ("F;32F", 1, 3, (32,), None),
    "RGB": ("RGB", 2, 1, (8,8,8), None),
    "RGBX": ("RGBX", 2, 1, (8,8,8,8), 0),
    "RGBA": ("RGBA", 2, 1, (8,8,8,8), 2),
    "CMYK": ("CMYK", 5, 1, (8,8,8,8), None),
    "YCbCr": ("YCbCr", 6, 1, (8,8,8), None),
    "LAB": ("LAB", 8, 1, (8,8,8), None),
}

def _cvt_res(value):
    # convert value to TIFF rational number -- (numerator, denominator)
    if type(value) in (type([]), type(())):
        assert(len(value) % 2 == 0)
        return value
    if type(value) == type(1):
        return (value, 1)
    value = float(value)
    return (int(value * 65536), 65536)

def _save(im, fp, filename):

    try:
        rawmode, photo, format, bits, extra = SAVE_INFO[im.mode]
    except KeyError:
        raise IOError, "cannot write mode %s as TIFF" % im.mode

    ifd = ImageFileDirectory()

    # tiff header (write via IFD to get everything right)
    fp.write(ifd.prefix + ifd.o16(42) + ifd.o32(8))

    ifd[IMAGEWIDTH] = im.size[0]
    ifd[IMAGELENGTH] = im.size[1]

    # additions written by Greg Couch, gregc@cgl.ucsf.edu
    # inspired by image-sig posting from Kevin Cazabon, kcazabon@home.com
    if hasattr(im, 'tag'):
        # preserve tags from original TIFF image file
        for key in (RESOLUTION_UNIT, X_RESOLUTION, Y_RESOLUTION):
            if im.tag.tagdata.has_key(key):
                ifd[key] = im.tag.tagdata.get(key)
    if im.encoderinfo.has_key("description"):
        ifd[IMAGEDESCRIPTION] = im.encoderinfo["description"]
    if im.encoderinfo.has_key("resolution"):
        ifd[X_RESOLUTION] = ifd[Y_RESOLUTION] \
                                = _cvt_res(im.encoderinfo["resolution"])
    if im.encoderinfo.has_key("x resolution"):
        ifd[X_RESOLUTION] = _cvt_res(im.encoderinfo["x resolution"])
    if im.encoderinfo.has_key("y resolution"):
        ifd[Y_RESOLUTION] = _cvt_res(im.encoderinfo["y resolution"])
    if im.encoderinfo.has_key("resolution unit"):
        unit = im.encoderinfo["resolution unit"]
        if unit == "inch":
            ifd[RESOLUTION_UNIT] = 2
        elif unit == "cm" or unit == "centimeter":
            ifd[RESOLUTION_UNIT] = 3
        else:
            ifd[RESOLUTION_UNIT] = 1
    if im.encoderinfo.has_key("software"):
        ifd[SOFTWARE] = im.encoderinfo["software"]
    if im.encoderinfo.has_key("date time"):
        ifd[DATE_TIME] = im.encoderinfo["date time"]
    if im.encoderinfo.has_key("artist"):
        ifd[ARTIST] = im.encoderinfo["artist"]
    if im.encoderinfo.has_key("copyright"):
        ifd[COPYRIGHT] = im.encoderinfo["copyright"]

    dpi = im.encoderinfo.get("dpi")
    if dpi:
        ifd[RESOLUTION_UNIT] = 1
        ifd[X_RESOLUTION] = _cvt_res(dpi[0])
        ifd[Y_RESOLUTION] = _cvt_res(dpi[1])

    if bits != (1,):
        ifd[BITSPERSAMPLE] = bits
        if len(bits) != 1:
            ifd[SAMPLESPERPIXEL] = len(bits)
    if extra is not None:
        ifd[EXTRASAMPLES] = extra
    if format != 1:
        ifd[SAMPLEFORMAT] = format

    ifd[PHOTOMETRIC_INTERPRETATION] = photo

    if im.mode == "P":
        lut = im.im.getpalette("RGB", "RGB;L")
        ifd[COLORMAP] = tuple(map(lambda v: ord(v) * 256, lut))

    # data orientation
    stride = len(bits) * ((im.size[0]*bits[0]+7)/8)
    ifd[ROWSPERSTRIP] = im.size[1]
    ifd[STRIPBYTECOUNTS] = stride * im.size[1]
    ifd[STRIPOFFSETS] = 0 # this is adjusted by IFD writer
    ifd[COMPRESSION] = 1 # no compression

    offset = ifd.save(fp)

    ImageFile._save(im, fp, [
        ("raw", (0,0)+im.size, offset, (rawmode, stride, 1))
        ])

#
# --------------------------------------------------------------------
# Register

Image.register_open("TIFF", TiffImageFile, _accept)
Image.register_save("TIFF", _save)

Image.register_extension("TIFF", ".tif")
Image.register_extension("TIFF", ".tiff")

Image.register_mime("TIFF", "image/tiff")