2023.02.07 12:04 "Re: [Tiff] tiffcrop tool ~ JPEG compression options produce wrong output", by L. E. Segovia

Hi,

A quick check tells me tiffcp does suffer from this bug:

> ~/Documents
> ❯ tiffcp -c jpeg -r 16 ./libtiff/test/images/quad-lzw-compat.tiff /tmp/test.tif
> LZWPreDecode: Warning, Old-style LZW codes, convert file.
>
> ~/Documents
> ❯ tiffinfo /tmp/test.tif
> === TIFF directory 0 ===
> TIFF Directory at offset 0x5b6e (23406)
>   Image Width: 512 Image Length: 384
>   Position: 0, 0
>   Bits/Sample: 8
>   Compression Scheme: JPEG
>   Photometric Interpretation: YCbCr
>   Orientation: row 0 top, col 0 lhs
>   Samples/Pixel: 3
>   Rows/Strip: 16
>   Planar Configuration: single image plane
>   Reference Black/White:
>      0:     0   255
>      1:   128   255
>      2:   128   255
>   JPEG Tables: (574 bytes)
>
> ~/Documents
> ❯ tiffcp -c jpeg:r -r 16 ./libtiff/test/images/quad-lzw-compat.tiff /tmp/test.tif
> LZWPreDecode: Warning, Old-style LZW codes, convert file.
>
> ~/Documents
> ❯ tiffinfo /tmp/test.tif
> === TIFF directory 0 ===
> TIFF Directory at offset 0xb8ce (47310)
>   Image Width: 512 Image Length: 384
>   Position: 0, 0
>   Bits/Sample: 8
>   Compression Scheme: JPEG
>   Photometric Interpretation: RGB color
>   Orientation: row 0 top, col 0 lhs
>   Samples/Pixel: 3
>   Rows/Strip: 16
>   Planar Configuration: single image plane
>   JPEG Tables: (289 bytes)
>
> ~/Documents
> ❯ tiffcp --version
> tiffcp: illegal option -- -
> LIBTIFF, Version 4.4.0
> Copyright (c) 1988-1996 Sam Leffler
> Copyright (c) 1991-1996 Silicon Graphics, Inc.

Looks like it's really really /really/ old, the interpretation was set here: https://gitlab.com/libtiff/libtiff/-/commit/cbc821458661bed9ab092568a556ffeaa065ab8d

Also, using `tiffcrop` here errors out consistently with:

> libtiff on  master [!] via C v13.0.0-clang via △ v3.25.2
> ❯ ./build/tools/tiffcrop -c jpeg:raw -r 16  ./test/images/quad-lzw-compat.tiff  /tmp/test.tif
> LZWPreDecode: Warning, Old-style LZW codes, convert file.
> JPEGSetupEncode: RowsPerStrip must be multiple of 8 for JPEG.
> /tmp/test.tif: Error, can't write strip 0.
> : Unable to write contiguous strip data for page 0.

Tiffcrop overrides whatever the user sets with the -r flag, so there's no way to tell it to use a more appropriate strip size: https://gitlab.com/libtiff/libtiff/-/blob/master/tools/tiffcrop.c#L7020

Best,

amyspark

amyspark 🌸 https://www.amyspark.me