AF-Photo v2.4.0(2240) Convert Format (colors) has strange effect

[pfi]

I changed Document>ConvertFormat>Format from RGB/8 to RGB/16 and found that sections of the image got darker.

See video - cursor follows lines of affected sections.  It is repeatable.  I have seen this before with other actions/adjustments on other images, so not a regression.

[stokerg]

Hi @pfi,

Have you only had this happen in the beta or has it also happened in the Release build?

I've tried replicating this in the beta and haven't been able to as of yet.  First thing i'd suggest, click Edit>Setting>Performance and disable Hardware Acceleration, restart Affinity and then try converting from RGB/8 to RGB/16 and see if you get the same issue.

[pfi]

Yes, I have seen it in a release version, but I seem to remember that it happened when using the HSL adjustment.

I have changed the hardware acceleration setting - disable/reset then enable/reset.  The issue has gone with either setting. But, this reminds me of something I have mentioned in another issue.  When I run a photo edit session I have Affinity Photo (AP) running for days and I cannot help but notice that AP, which is already frustratingly slow when cloning, healing or dodging,  starts getting slower and deteriorating. AP then shows artifacts like banding, or the issue of this discussion, or in many cases AP crashing, or hanging for 10s of seconds with 'AP not responding'.  And now, that I think about it, that was the issue with the just mentioned HSL adjustment.  A reset of AP got rid of the issue,  and I wonder when changing the H/W acceleration with a subsequent reset fixed this particular issue as well?

[NotMyFault]

Can you share the file? It is probably one of the adjustments or live filters (unsharp mask) which is very sensitive to zoom level.

Please try a „merge visible“ in both color depths, and compare those visually at 100% zoom level.

Whenever you have any noise or sharpening, or fine details with high contrast, this can happen due to mipmap rendering.

Color format changes will impact areas with partial transparency, by masks or layer fx effects which include blur. You may get steep alpha value changes in areas where alpha is almost zero. This can lead to exaggerated rendering artifacts especially when zoomed out like in your case.

Zoom the attached file to 100%, 200%, 50%, and any levels in between. Let Photo a few seconds when changing zoom level to reach full rendering resolution. You will spot insane rendering artifacts (false color, false lightness).

Unfortunately this is by design, and requests to add features giving trustful preview where not implemented yet.

rendering bug at 100% rasterized blend rangeafphoto.afphoto

Edited January 23, 2024 by NotMyFault
PS: this is only best guess /assumption before having chance to inspect the actual file

[pfi]

Hi NotMyFault, sorry for the late reply.

As I mentioned above, after A-Photo reset (after hardware acceleration setting change)  I was not able to reproduce the problem and, unfortunately, I did not save the project before the reset.

I am happy to share the image, but I don't think you'll be able to reproduce the issue.

btw.  My usual workflow is:

- run a macro, which makes a copy of the background image and ads my most often used adjustments and filters, most unmodified, some with minor pre-adjustments.

- in this particular image I had a few clone brush actions, dodge and burn, and I used the perspective tool to balance up the image.  (I am quite suspicious of dodge and burn and clone and heal actions, but maybe that has to do with the 'long' lag)

- I then do adjustments - Unsharp Mask and Noise Reduction are usually last - Affinity Photo runs even slower with these two enabled.

(I want to add color format RGB/16 to the macro)

When weird stuff happens again, I will try to remember and do your suggestions. - thanks

[NotMyFault]

2 hours ago, pfi said:

When weird stuff happens again, I will try to remember and do your suggestions. - thanks

Thanks for your reply.

Most important: in case you want to file a bug report, always attach an afphoto file where having this issue. Filing a bug report and not saving the actual file can cause waist of time for all who try to work on the issue, as nobody will be able to reproduce.

2 hours ago, pfi said:

run a macro, which makes a copy of the background image and ads my most often used adjustments and filters, most unmodified, some with minor pre-adjustments.

That is important.