Apply ACEs Display Transformation When Converting to 8/16 bit

[Tyler Bay]

Hello Affinity,

I am trying to convert a 32 bit image - rendered with Redshift/Houdini - into an 8 or 16 bit image with the proper OCIO/ACEs transformation baked into the ICC profile.

At the moment, I am forced to rely in the ICC profile instead of ACEs when doing this transformation to 8 or 16 bit.

This is, however, an incorrect workflow because of the fact that it will clip highlights, does not account for the change in ACEs CG primaries which results in desaturation, and is generally not as accurate as what is implemented with ACEs due to the order of operations during the transformation.

I am aware that there is a suggested fix for this by converting to 8/16 and then applying a 2.2 gamma curve reduction once the sRGB ICC has been applied via a live filter layer.

However, as mentioned above, I am still left with clipped highlights and desaturation.

 

Is there a way to apply an ICC profile which does nothing to the image?  Or, ideally, a way to convert to 8/16 bit without altering the pixel data in any way.

 

Thanks in advance,

 

-  Tyler

 

 

[kirkt]

@Tyler Bay It's not clear what you are trying to do - when you convert from 32bit to a lower bit depth, is your intention to end up with an image that is in ACES but at the lower bit depth, or are you also converting to another color space?  What ICC profile are you forced to rely upon instead of ACES?  What does this mean?  What OCIO transform are you using to get to your desired output?  What are you trying to "bake in" to your image?

Also - how is your color set up in the Preferences?  Is ACES CG your 32bit working space?  What is your Display Transform set to I the 32-bit preview panel?

it would be helpful to describe your workflow and the desired result (ie., "I want to end up with a linear 16bit image with the ACES color preserved") more explicitly.

Kirk

[walt.farrell]

Welcome to the Serif Affinity forums, @Tyler Bay.

I'm not sure they are applicable to your desired workflow, but have you watched the two official Affinity Photo tutorials that deal with OCIO?

If you visit https://affinity.serif.com/en-us/tutorials/photo/desktop/ and type OCIO into the search box, you should see two tutorials that may be relevant.

[kirkt]

Also - "applying" a profile should not change the underlying RGB numbers, just how those numbers are interpreted to display them.  In contrast, "converting" with an ICC profile will change the numbers of the pixels to preserve the original appearance of the color in the new, destination color profile space.

Kirk