* Improve encoding of TIFF tags
- Pass tagtype from v2 directory to libtiff encoder, instead of
autodetecting type.
- Use explicit types. E.g. uint32_t for TIFF_LONG to fix issues on
platforms with 64bit longs.
- Add support for multiple values (arrays). Requires type in v2
directory and values must be passed as a tuple.
- Add support for signed types (e.g. TIFFTypes.TIFF_SIGNED_SHORT).
Co-authored-by: Andrew Murray <radarhere@users.noreply.github.com>
Old-style JPEG compression in TIFFs are able to be read using Strip/Tile APIs. Although, it should be possible to read them using Scanline API, it does not work for some reason. Anyway, reading subsampled YCbCr formats through Strip/Tile/Scanline libtiff API does not de-subsample the data, so caller should unpack data to whatever format is appropriate. New-style JPEG compressed images were already read through libtiff as RGB images (https://github.com/python-pillow/Pillow/pull/3227). Unfortunately, there is no flag to ask libtiff to de-subsample old jpeg, but it provides a way to read any image as 32bit RGBA. This commit adds ability to read old-style JPEG TIFFs through reading *all* YCbCr images as RGBX using Tile and Strip reading API. This supersedes previous work (PR #3227) to read new-style JPEG-TIFFs.
JPEG-related tiff pseudo-tags are registered only when tiff image has jpeg compression. Trying to set TIFFTAG_JPEGCOLORMODE on non jpeg-compressed file prints error "Unknown pseudo-tag 65538".
