RGB32, blend range

[NotMyFault]

Hi,

 

I have a simple sunset image, and try to blend 2 layers using blend ranges.

To my surprise, I get a fully saturated green rendering despite the info panel shows no change in hue in selected positions.

Any ideas?

Does blend ranges in RGB/32 (linear) behave different from gamma corrected color spaces?

Blend range 100% -> top image fully opaque

blend range on right node reduced by 1% to 99%: rendering becomes green, despite info panel does not chnage

Another issue:

For upload, I cropped the original 6k x 4k file to 500x200px, rasterised & trimmed both pixel layers and used save as (without history). The file is still >300 MB large, beyond any reasonable size.

 

It seems blend ranges do not work correct in case images contain color values >1.0

 

PS: The file "rgb32 blend range bug" is far smaller and cn be used to reproduce the issue.rgb32 blend ramge bug.afphoto

It shows a gradient from 0 to 4 for RGB (and grey) over x-axis.

Once you start to change any node of the blend range, either source or destination, the rendering gets wrong.

Activate the scope panel in RGB parade mode to spot the issue. You need to activate the exposure adjustment ro reduce the color values into visible range to use scope, as it misses the option to increase max (like histogram).

 

821246897_IMG_8654blendrangecropped.afphoto

[walt.farrell]

15 minutes ago, NotMyFault said:

For upload, I cropped the original 6k x 4k file to 500x200px, rasterised & trimmed both pixel layers and used save as (without history). The file is still >300 MB large, beyond any reasonable size.

Did you delete the initial Snapshot?

[NotMyFault]

12 minutes ago, walt.farrell said:

Did you delete the initial Snapshot?

no, that explains the size issue.

[Lisbon]

2 hours ago, NotMyFault said:

Any ideas?

Nope.

But the problem goes away if you add an adjustment layer, as a child, to the top layer.
Curves, Levels, HSL, will work.
Absolutely no idea why this works.

(Maybe the top layer is feeling lonely)

[NotMyFault]

11 hours ago, Lisbon said:

But the problem goes away if you add an adjustment layer, as a child, to the top layer.
Curves, Levels, HSL, will work.

not fully, it is replaced by a different problem.

If i activate a nested exposure adjustment (with „0“ setting), the colors will change, not visible as only the >1.0 values are impacted. 

[Lisbon]

Another interesting thing has to do with the "Blend gamma" value inside "Blend options".
If you change from 2.2 to 2.1 or 2.3, the green also disappears.

[NotMyFault]

4 minutes ago, Lisbon said:

Another interesting thing has to do with the "Blend gamma" value inside "Blend options".
If you change from 2.2 to 2.1 or 2.3, the green also disappears.

Yes, can confirm. Seems like someone hardcore this 2.2 value into the blende formula.

When i remover it right, all blend operations are done in an specific color format (HSV?), and there are lot of back and forth conversions. Using linear gamma would normally require to change the blend gamma of all layers manually to 1 for all layers. Affinity will create new layers always using the global default value of 2.2, which might be unsuitable in this context

[NotMyFault]

even more interesting: blend gamma is normally ignored in RGB/32. It has no effect on layer blending. Except in this strange case.

 

layers with blend gamma 1 / 3 in RGB/16: visible effect (step 2)

layers with BG 1 / 3 in RGB/32: no effect (step 1)

rgb32 bR step 1.afphoto rgb32 bR step 2.afphoto

[NotMyFault]

bump - any comments from mods?

[Leigh]

On 8/9/2022 at 4:45 PM, NotMyFault said:

bump - any comments from mods?

Do you get the same result with Metal enabled and disabled? Only asking because I can only replicate the green area with OpenCL enabled on Windows.

[NotMyFault]

Seems to related to Metal / HW acceleration on Mac.

[Leigh]

Thanks for confirming. Will log with the developers - thanks for letting us know.