Lab Mode and 32bit

[j3rry]

I always thought that in LAB mode the brightness setting has little or no effect on the colour, and in 16bit mode it does. Only in 32bit mode do I see a strong increase in colour. The behaviour is the same in the release version and the current beta.

I attach a video and the afphoto (from the beta version and from the release).

 

Maybe I`m wrong with my knowledge ...

 

1907_Poskaer_Steingrab_0052-beta.afphoto 1907_Poskaer_Steingrab_0052v2.afphoto

[Callum]

Hi Jerry,

When I try this here I'm seeing a reasonable change in colour using both 32bit and 16bit colour formats for my document. Please could you provide another screen recording demonstrating the different between 32bit and 16bit you are referring to?

Thanks
C

[j3rry]

Hi Callum,

Here is the requested screen recording, I see a big difference between 16bit and 32bit.

 

[lepr]

8 hours ago, j3rry said:

I see a big difference between 16bit and 32bit.

Yes, there is a big difference.

The LAB Curves Adjustment assumes source RGB values are gamma encoded, even when they are really linear as in a RGB/32 document. That false assumption is a bug carried from Affinity 1.x.

To make LAB Curves in a RGB/32 document give the same result as it does in a RGB/16 or RGB/8 document, it needs to be preceded by a gamma encoding adjustment and followed by a gamma decoding adjustment.

Attached is an example.

LAB Curves in linear RGB document.afphoto

[j3rry]

@‘‘‘,
many thanks, I was not aware of the additional gamma corrections. The Curve tool  works really ok with the changes in your document.