3-channel 48bit TIFF is wrongly read as 4-channel (with alpha)
I try scanning to 48bit (16 bit per channel) TIFF with VueScan, but GIMP reads it wrong, forwarding the data partially to alpha-channel. Probably, it is interpreting 3-channel/16bit image as 4-channel/12bit encoded. If not, I have no Idea where that 4-th alpha channel comes from. It is not blank, but filled with some ghost from original image. Probably other channels are also damaged, but it is not obvious when seen by eyes, to my surprise.
There are also error messages appear: "Incompatible type for 'RichTIFFIPTC'; tag ignored" and "Alpha channel type not defined for file C:....tiff. Assuming alpha is not premultiplied."
GIMP 2.10.12 @ Windows 7 x64