Linear/unstretched TIFF files being misinterpreted as HDR

[Dirkpitt3959]

I'm trying to develop a work flow for milkyway panoramas that use a stack of multiple images for each panel.  That is, I take multiple exposures at each position and stack them, then stitch those into the panorama.  

The stacking software (pixinsight) outputs a TIFF with linear/unstretched data.  When I try to bring that into PTGui, it gives an error that HDR images are only supported by the pro version.  These are not HDR, but I assume something about the file format makes it think they are.  I can bring in the raw images just fine, but those are not stacked.  I can develop the stacked images, and then PTGui will accept the developed TIFF, but it's difficult to get each panel developed in a seamless way (one panel might be much lighter or darker than another).  I was hoping that if I made the panorama with the linear images and then stretched it afterward it would resolve that issue.  

Any ideas what is prompting PTGui to treat the tiff as HDR?  

There are file type options here that I am not familiar with.  Are any of these other than TIFF, FITS, or XISF (which I have already tried) lossless?  

Thanks

[PTGui Support]

Hi,

Your TIFF file is in 'floating point' format, 32 bit per channel.
Floating point images can support a very high dynamic range (100s of
stops), hence PTGui treats such a file as a HDR format. But this
requires PTGui Pro.

Linear data doesn't strictly require floating point though. If you save
your image as 16 bit TIFF it should work. I would assume pixinsight is
capable of this but I'm not sure.

Kind regards,

Joost Nieuwenhuijse
www.ptgui.com

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[Dirkpitt3959]

That was just what I needed.  Thank you!