Handling of semitransparent canvas in app and export

[NotMyFault]

Affinity handles areas of semitransparency wrong both rendering inside the app and exported files.

1. create a new document. Cmyk, transparent canvas off
2. add a rectangle over the full canvas.
3. set a gradient in white color, but alpha from 100% (left side) to 0% (right side)
4. add another rectangle and set to 100% cyan, 50% alpha, solid color.

expected: the rendered and exported color must be 100% cyan. It might be lighter cyan to the right.

observed: cyan gets darker on the right. You can spot this by scope panel or channels panel.

For exported files, the rendering differs and shows lighter area in the center of the rectangle.

This affects all 3 apps, V1 and V2, and probably all platforms

There are multiple bugs:

• Affinity ignores document setting for canvas transparency at export, depending on export format. This has been raised before
• Affinity treats white (transparency off) canvas differently vs. A white filled layer during rendering inside the app
• Affinity treats white canvas differently when exporting (and results differ depending on export setting)

 

 

semitransparent canvas bug.afphoto

[NotMyFault]

Another example:

if you put a white rectangle behind other layers with blend mode color burn the result differs from a by default nontransparent white canvas.

 

 

[stokerg]

Hi @NotMyFault,

We do already have an issue with how Affinity handles transparency when using CMYK logged with the Developers.

I suspect what you are reporting is covered by that, but i'll make a new bug and link it to the other, just to be sure nothing is missed