Bug: make the tiff encoder spec conformant to avoid corrupted TIFF on MacOS

[stephane-archer]

This image is 3840 × 2160:
testHorizontal.zip

The copyResize function silently produces corrupted TIFF output when resizing an image to a height that is not a multiple of the original height (e.g., 1234). However, it works correctly for heights like 720 or 1024.

    var resizeImage = img.copyResize(refImageCompatibleImage, height: 1234);
    img.Image editedImage = img.adjustColor(
      resizeImage,
      brightness: brightness,
    );
    Uint8List editedImageEncoded = img.encodeTiff(editedImage);
    File editedImageFile = await getNewTempFile("EditedImage", ".tiff");
    await editedImageFile.create(exclusive: true);
    await editedImageFile.writeAsBytes(editedImageEncoded);
    return editedImageFile.path;

Issues

• Silent Failure: The function does not throw an error for unsupported heights.
• Unexpected Behavior: The function should resize to any height, or document constraints and enforce them via exceptions.

[brendan-duncan]

I'm not seeing the error or corruption from copyResize. I ran a test on your image using

      final img =
      decodeJpg(File('test/_data/jpg/testHorizontal.jpg').readAsBytesSync())!;
      final i0 = copyResize(img, height: 1234);
      final editedImage = adjustColor(
        i0,
        brightness: 0.75,
      );
      expect(i0.width, equals(2194));
      expect(i0.height, equals(1234));
      File('$testOutputPath/transform/copyResize_jpg.tif')
        ..createSync(recursive: true)
        ..writeAsBytesSync(encodeTiff(editedImage));
    });

And that produced this TIFF,
copyResize_jpg.zip

[stephane-archer]

@brendan-duncan the tiff produced that you linked can't be read in MacOS and result in error when displaying using flutter

[stephane-archer]

I don't know what makes this tiff incompatible with MacOS, is there anything special with that tiff? Could it be an error in the files or a structure issue in the file? Bit Depth? Color Profile? Metadata?

[stephane-archer]

there seems to be error in the produced file:

identify -verbose copyResize_jpg.tif
identify: Invalid TIFF directory; tags are not sorted in ascending order. `TIFFReadDirectoryCheckOrder' @ warning/tiff.c/TIFFWarnings/939.
identify: Nonstandard tile width 2194, convert file. `copyResize_jpg.tif' @ warning/tiff.c/TIFFWarnings/939.
identify: Nonstandard tile length 1234, convert file. `copyResize_jpg.tif' @ warning/tiff.c/TIFFWarnings/939.
identify: Nonstandard tile width 2194, convert file. `copyResize_jpg.tif' @ warning/tiff.c/TIFFWarnings/939.
identify: Nonstandard tile length 1234, convert file. `copyResize_jpg.tif' @ warning/tiff.c/TIFFWarnings/939.

[stephane-archer]

tiffinfo copyResize_jpg.tif
TIFFReadDirectoryCheckOrder: Warning, Invalid TIFF directory; tags are not sorted in ascending order.
copyResize_jpg.tif: Warning, Nonstandard tile width 2194, convert file.
copyResize_jpg.tif: Warning, Nonstandard tile length 1234, convert file.

[stephane-archer]

• The warning Invalid TIFF directory; tags are not sorted in ascending order indicates that the TIFF file's tags are not in the standard order. macOS Preview may have stricter requirements for properly ordered tags compared to other platforms.
• The warnings Nonstandard tile width 2194 and Nonstandard tile length 1234 suggest that the file uses non-standard tile sizes. These might not be handled correctly by macOS's TIFF reader, as standard tiles are typically powers of 2 (e.g., 256x256).

The last point is most likely the main issue and could explain why some resolutions work for copyResize.

[brendan-duncan]

I'll take a look at the TIFF encoder on macOS as soon as I get a chance. TIFF is such an awful format. It can do everything, but the problem is that it can do everything and no one can agree on what it should do.

[brendan-duncan]

According to libtiff, http://www.simplesystems.org/libtiff/functions/TIFFtile.html, tileWidth and tileHeight have to be a multiple of 16 to be spec conformant. I'll look into making that happen.