Hello -- I've been posting around (gimp-user-list, gimp-developer-list, hugin forum) in hopes of helping get to the bottom of interoperability issues relating to high bit-depth tiffs.
I understand that g'mic outputs 32bit float (and that ,ushort can be used to force 16bit integer) and that many programs don't support this, and that isn't g'mic's fault. But I'm wondering if it would be possible to bring some of the free software world in line with itself. If this is not something useful for g'mic folks to look at, then please ignore. I just don't know which part of the pipeline needs adjusting, so I'm casting a wider net.
Here is a zip file of small demo images: http://caseyconnor.org/pub/image/smallexample2.zip
The only editor/viewer that seems to open everything as expected is Luminance HDR. Gimp, hugin, etc, all have issues. I read here that g'mic uses a legacy standard in it's 32bit format, so maybe this is moot for g'mic, but I post this in the faint hope that it might be useful.
Files in the zip:
original.tif -- 16bit integer image exported from Canon Digital Photo Professional
original2.tif -- a copy of original.tif used for processing
aligned000?.tif - the result of "align_image_stack --gpu -C -a aligned original*.tif
aligned_then_gmic.tif -- the result of gmic -median_files aligned*.tif -o aligned_then_gmic.tif
hugin_output.tif -- the result of running a simple rectilinear stitch on aligned_then_gmic.tif
aligned_then_gmic.pto -- the pto used to do that
other_example.tif -- another strangely-behaving .tif file in case it's useful (hugin can't open this one, maybe? But Luminance HDR can.)
...none of the processed .tif files open properly in GIMP, but some of them can be recovered by changing to an integer precision. hugin_output.tif can not be recovered (though again, Luminance HDR opens it fine, and so does hugin).
Let me know if more examples would be useful.
My test setup: Kubuntu 16.10, otto-kesselgulasch gimp 2944dbd688. (Also happens with pixls.us gimps. Happens on linux and windows.) G'MIC 2.0.0. pre-release #013117. align_image_stack version 2016.3.0.85fedd083c55