12-bit images are saved with errors

[olejorik]

When running some old code on an updated environment, I noticed that 12-bit images (that is, with elements of Gray{N4f12} type) are saved with errors.
I have checked with the old version of TiffImages.jl; it works as expected. Here is a MWE:

 ]activate --temp
 ]add [email protected]
 ]add ImageCore, FileIO

using TiffImages, ImageCore, FileIO
ttt = ((1:100)' .+ (1:100) )/200
sss = Gray{N4f12}.(TTT)
save("im4f12_old.tif",sss)

The result is this

If you run the same MLE without specifying the version for TiffImages, the result is like this:

I'm on Windows, julia 1.11.2.

[chrstphrbrns]

Neither version is saving the data correctly, although the older version fails less spectacularly than the current one. Writing files with unusual bit depths has probably never been supported

Fortunately, I had done some preparatory work for this scenario a while back, so I've been able to put a PR together without too much effort

[olejorik]

Neither version is saving the data correctly, although the older version fails less spectacularly than the current one. Writing files with unusual bit depths has probably never been supported

Maybe there is some error in what is saved by the old version, but I'm not aware of it. The data are in full correspondence with what I've got from a 12-bit camera.

[chrstphrbrns]

The actual bottom-right pixel in your example is Gray{N4f12}(1.0)

If you load the file with v0.6.3 you'll see it represented as Gray{N0f16}(0.06249)

[tlnagy]

Should be fixed on latest master thanks to @chrstphrbrns!