1.98: TIFF Tags

[yaunxn]

* TIFF tags order - http://newsgroup.xnview.com/viewtopic.php?f=36&t=20222

There are still some issues present.

First, if a Model tag (272) is present in the source file, it is always added after all other tags, i.e. tags are still not sorted in ascending order.
Please note that "Export" operation removes the Model (272) tag, while "Save as" does not.
tiffdump output:

Code: Select all

tiffdump test_gray8_save_as.tif

test_gray8_save_as.tif:
Magic: 0x4949 <little-endian> Version: 0x2a
Directory 0: offset 8 (0x8) next 0 (0)
ImageWidth (256) LONG (4) 1<2480>
ImageLength (257) LONG (4) 1<3506>
BitsPerSample (258) SHORT (3) 1<8>
Compression (259) SHORT (3) 1<32946>
Photometric (262) SHORT (3) 1<1>
StripOffsets (273) LONG (4) 1<272>
SamplesPerPixel (277) SHORT (3) 1<1>
RowsPerStrip (278) LONG (4) 1<3506>
StripByteCounts (279) LONG (4) 1<6732163>
XResolution (282) RATIONAL (5) 1<300>
YResolution (283) RATIONAL (5) 1<300>
PlanarConfig (284) SHORT (3) 1<1>
ResolutionUnit (296) SHORT (3) 1<2>
Software (305) ASCII (2) 32<LIBFORMAT (c) Pierre-e G ...>
Predictor (317) SHORT (3) 1<1>
Model (272) ASCII (2) 17<PSC 1200        \0>     <- I'm talking about this

Second, xnview always adds Predictor (317) tag to the file, regardless of compression, which is, I believe, an error, because in TIFF specification, section 14, it is written that

A predictor is a mathematical operator that is applied to the image data before an encoding scheme is applied.
Currently this field is used only with LZW (Compression=5) encoding because LZW is probably the only TIFF encoding scheme that benefits significantly from a predictor step.

Those two issues cause warnings in libtiff based software, such as imagemagick & GIMP.

Thank you.

[xnview]

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