Dcraw options inside PTGui

[Fabien]

Hello,

I've been experimenting a bit with the Unity HDRI probe workflow (http://blog.selfshadow.com/publications/s2016-shading-course/unity/s2016_pbs_unity_hdri.pdf).

To summarize the steps, here is what they advise to do:
- convert the RAW files from the cameras to non white balanced Tiff 16 bits depth linear gamma using dcraw (-4 -T flags)
- fix chromatic abberations, fringing, vignetting in the software of your choice

- convert the Tiff16 to Tiff32 because PTGui doesn't acknowledge 16 bits files as linear gamma files.

- import in PTGui

In my case, I think fixing lens issues isn't really important, but making sure that the luminance and color information from the RAW is properly preserved to create the HDR probe is.

I have compared this workflow to the simplest one, using the RAW files directly in PTGui, and there is indeed a slight difference in tones and intensity values.

Since PTGui is actually using dcraw, it's quite a waste of time to have to go through dcraw (and photoshop for 16 to 32 bits conversion) before importing to PTGui, I was wondering if it would be possible to expose the dcraw options inside PTGui, and also give the possibility to import Tiff 16bits depth files as linear?

Cheers,

Fabien

[Fabien]

So I'm trying to get rid of that extra 16 to 32 bits step. With some information on this support group and testing stuff myself, I managed to find dcraw settings to create the Tiff 16 with sRGB curve and proper color space.
Everything looks correct (comparing linear 32 bits to the gamma corrected 16 bits ones).

But when creating the HDR, I get banding issues. Exporting the layers separately, I'm getting highlight clamping, which I assume is the cause of the banding:

Do you know what is going on and if there is a way to fix that?

Thanks!

[Jason PTG]

Hey Fabien, I am in the same ship following the same Siggraph course note. From your thumbnails, I can't tell if the banding happens in your TIFF linear or TIFF sRGB set?

I had banding issue with TIFF linear 32-bit when using older version of PTGui but as soon as I upgrade to the latest 10.0.15, the banding issue is gone as least in my tests.

Like your said, would be great to have an option to tell PTGui to treat 16-bit linear TIFFs not as sRGB ones so we don't need to convert 32-bit TIFFs externally. Have you found anything new in this regard?

- Jason