Alpha artifacts in PNG export

[arqpv]

Hello everyone.
I've been having this problem for a while now and so far I have not found people talking about it.
After I export my renders from Corona Image Editor into PNG format, I load those into photoshop (beauty pass) to make a few adjustments and add backgrounds.
The png file already has alpha applied.
When I zoom in many times I've seen these artifact lines, or sometimes semi-transparent pixels when they should be completely opaque.
Am I doing something wrong?

Using 1.7.2 here. Rendering to 4% noise and adding 0.4 denoise pass. CXR -> corona image editor -> PNG workflow.
I'm attaching a few captures to show the problem, and my layers in photoshop. Full rez alpha channel image. When you zoom in you can see the pattern it's creating on the bottom right quarter of the image.

Any input will be appreciated!!!!

[maru]

Is this rendered locally on just one computer, or using Corona's DR or Backburner?
Do you have bloom and/or glare enabled?

Have you tried with a newer version? (1.7 hf4 or daily builds)

[arqpv]

Hello Maru thanks for the reply.

It has happened to me in both DR and locally. This one was locally rendered. No backburner.
Bloom glare I always have enabled.

At home I have 1.7.4 but I have not tested it extensively. Will give it a try as well. Thanks for the suggestion!

[diffuus]

I had the same problem. I never saw the lines, but I experienced the grid in several images. (usually the darker area's).
It was linked to the export of the CXR file format. When rendering to TGA, the problem was no longer there.
Although it is a great concept, I stopped using CXR for this and other reasons (because sometimes I even got corrupted CXR files - see my other post)

[maru]

I did not manage to reproduce the issue using newest daily build of Corona.
I think it might be caused by this issue, which is already fixed: https://forum.corona-renderer.com/index.php?topic=19423.0

@xkuruma @diffuus please try reproducing your issues using the newest daily build: https://coronarenderer.freshdesk.com/support/solutions/articles/5000570015
If it works fine, then it means it's fixed.
If you can still reproduce this, please send us a report to support@corona-renderer.com and it will be investigated further.

[arqpv]

Thanks Maru.

So I tested it and here's what happened:

1.7.4:
Sharpen/Blur ON: shows the problem
Sharpen/Blur OFF: does not show the problem

May 15th 2018 Daily Build:
both sharpen/blur ON and OFF do not show the problem, so it's already been patched.

So it was definitely related to the sharpen/blur feature, and hopefully in 2.0 it does not come back.
BTW loving the toolbar in the daily build!

[maru]

Cool! Moving to resolved bugs then.
But of course please re-report if you encounter this in newer versions.