PNG Black&White Layer inserts as Greyscale after Copy&Paste

[Walter2711]

Mac OS 12.6.3 (21G419) / Affinity Photo2.0.4

Dear Affinity helpdesk,

I have a dithered PNG File which contains only black and white pixels.
Now I crop a part of it and export it as a new PNG file.
After opening the cropped PNG and compare it to the original file everything is ok. B&W Pixels.

Now I copy the layer of the cropped PNG and paste it as new layer to the original PNG and it suddenly becomes a blurry greyscale image.

After repeating the process it occasionally inserts correctly. Often not.

Screenshot zoomed: Left original | right pasted

What has happened? Please help. Thank you!

regards

Walter

Affinity Photo Bug Paste PNG Layer_1.afphoto Affinity Photo Bug Paste PNG Layer_2.afphoto

[Paul Mudditt]

Welcome to the forums !

Looks like a pixel alignment issues, check your snapping options under the snapping menu to force pixel alingment.

[Walter2711]

3 minutes ago, Paul Mudditt said:

Welcome to the forums !

Looks like a pixel alignment issues, check your snapping options under the snapping menu to force pixel alingment.

Thank you for the quick reply. Might look like alignment but the PNG is not transparent. What you see is the image itself that gets disturbed after pasting.

[Hangman]

Hi @Walter2711 and welcome to the forums...

@Paul Mudditt is correct (he beat me to it)...

When you paste your cropped B/W PNG file into your document it pastes to the top left of your file and looks correct, i.e., no partial pixel alignment. Before moving it, if you turn Force Pixel Alignment on in the context toolbar you will see everything looks as you want it to when you then move the image...

I would perhaps make a complete new image if possible including both elements otherwise this could be an issue OR work on the file in Affinity Designer where you won't have the same problem.

[Walter2711]

Thank you also for replying. I am afraid I did not explain it good enough. Did you open the files I added? One is the cropped PNG and the other is the original with the cropped inserted as new layer. Maybe then it gets clearer then. It's not an adjustment problem. The inserted layer has the grey pixels IN it right after pasting. 

Edited March 14, 2023 by Walter2711

[Hangman]

16 minutes ago, Walter2711 said:

Thank you also for replying. I am afraid I did not explain it good enough. Did you open the files I added? One is the cropped PNG and the other is the original with the cropped inserted as new layer. Maybe then it gets clearer then. It's not an adjustment problem. 

Hi Walter, that's exactly what I did and this is simply a pixel alignment issue, hopefully the screen recording will make things a little clearer... as mentioned above, once you've pasted your cropped image, switch Force Pixel Alignment on in the context toolbar and then you won't or at least shouldn't see the problem when you move your pasted cropped image...

[Walter2711]

Yep! Got it. No grey pixels anymore. Thank you very much for your help! HERO of the day!

What puzzled me was that it sometimes seemed to occur and sometimes not. I wasn't aware that it could have been caused by solely moving the image.

Can you tell me what happens here?

Edited March 14, 2023 by Walter2711

[Hangman]

5 minutes ago, Walter2711 said:

Can you tell me what happens here?

Basically, because the image can be moved by fractions of a pixel you are seeing the the effect of anti-aliasing where the pixels aren't perfectly pixel aligned... this hopefully demonstrates what happens when you move the image by fractions of pixels, you will see, when positioned anywhere other than at whole pixel values, the effect of anti-aliasing to display sub pixel positioning. As soon as the image is perfectly pixel aligned no anti-aliaising is visible...

[Walter2711]

Oh wow. This is perfect. Thank you for you help. Awesome!

Made my day. 

[Hangman]

That's no probelm at all, glad to have been able to help...