Linear 16bit TIFF input incorrectly handled as sRGB by PTGui

[seba...@unity3d.com]

Hi, 

We use our own conversion from RAW format to TIFF for various purpose (with Dcraw)

then  we would like to use PTGui for stitching and HDR reconstruction.

Our current trouble is that when we input our linear 16bit TIFF image to PTGui it automatically consider that this TIFF is in sRGB, exactly like if we provide a JPEG.

This is a problem for us because our TIFF image is in linear RGB, not in sRGB.

PTGui perform the conversion from sRGB to linear on our TIFF file, then convert to HDR which is wrong. This has been confirm by using Nuke to transform our TIFF to sRGB before feeding it to PTGui (even if it make no sense here).

So our question, how can we tell to PTgui that our input image is already in linear format ?

Thanks

[seba...@unity3d.com]

Cross post the answer because I have ask two times the same questoin:

"

Hi Sebastien, 

Currently PTGui is hard coded to assume that a 16 bit file is nonlinear 
and thus it will use (and optimize) the camera curve as shown in the HDR 
tab. It's also hardwired to assume that a 32 bit (floating point) file 
is always in linear space; for 32 bit files the camera curve is ignored. 
I'd be the first to admit that this is a bit quirky. 

So the workaround for now is to convert your files to floating point 
(tiff or exr). 

Kind regards, 

New House Internet Services BV 
Joost Nieuwenhuijse