[Gimp-user] troubles with 32bit float...

[Casey Connor <gimp-user-list caseyconnor org>]

I'm having lots of issues with the 32bit tiffs that come out of G'MIC 
CLI processing in Linux (Kubuntu 16.10 in my case).

They don't open properly in GIMP, or most any other software. There is 
clearly something going wrong somewhere, but I'm not sure where to file 
a report as I'm not sure where the root cause may be (GIMP, underlying 
tiff libraries, or G'MIC, etc.) If anyone has any insight, I'd 
appreciate it.

When I apply a -median_files filter with G'MIC, it generates a 32bit 
float file that opens as all-white in GIMP. But I can change the 
precision (in GIMP) from 32bit-float to any integer format, and the 
image suddenly appears and I can work with it just fine. Here is a 
demonstration image: http://caseyconnor.org/pub/image/32bitfloat.zip (145MB)

Can anyone reproduce that? I've asked here before without luck, but I've 
seen on other forums that I'm not the only one with this issue. (This 
happens in any recent version of GIMP on Linux or Windows for me, but 
most recently tested in otto-kesselgulasch repo commit 2944dbd.)

I tried to generate a smaller simple example starting with a 100x100 
pixel image, 16bit integer precision (same thing happens with 8bit): I 
make a simple gradient, save it to png or tif, process through G'MIC, 
and open the result in GIMP. Result: image is all white, and in this 
case changing precision does *not* make the real image appear -- I can't 
see the image no matter what I do. Here is a zip file with the original 
and the gmic processed version that won't open in GIMP: 
http://caseyconnor.org/pub/image/smallexample.zip

The KDE image viewer (gwenview) shows the image differently every time 
it opens it: sometimes a corrupted version, sometimes a line across a 
black background, and the line changes color every time the image is 
opened. (I mention this only in case it points at some system library 
issue.)

If I open the 32bit float G'MIC images in Hugin, they open fine, but the 
resulting 32bit float output from Hugin can not be opened in or 
processed by GIMP in linux or windows.

AN important note: I can open all of these images (post-G'MIC, big image 
or small 100x100 image) in Luminance HDR: it seems to have no trouble 
with them.

Any thoughts? Are there GIMP bugs here to be addressed? Can anyone 
reproduce this?

I've had some success using G'MIC in 16bit integer mode (by appending 
",ushort" to the file name); my main goal here is to sort these bugs out.

Thanks!