Failure to load 4-bit grayscale TIFF layers
We are setting up a TIFF-based modding pipeline in vange-rs, and the current format we want to work with consists of 5 layers: 3 grayscale 8-bit ones followed by 2 grayscale 4-bits. Loading such a TIFF in GIMP (tried 2.10.8 on Windows) appears to show that it fails to properly load the 4-bit layers. It looks like it tries to advance 16 bit per texel instead of 4 bit:
As a supporting evidence, note that our TIFF is loaded correctly in:
- Gnome Document Viewer
- Windows Photo Viewer
- IrfanView
I don't know if the bug is caused by the general lack of support for 4-bit grayscale modes of TIFF, or just complicated/confused by the fact that there are layers of different bit width. Unfortunately, attaching the real TIFF is not an option since our levels are huge, and the file size is about 130Mb.