Scaled and snapped image objects have slight translucent fringe

[m888]

@KarlLegion per your request, separating this bug report into it's own topic.

Reproduced in Affinity Photo V2.0.3 on Windows 10. A sample project is attached that demonstrates the problem.

A simple test reproduces the bug:

• drag a 200x200 white square into a 210x210 canvas
• scale it to fill the canvas with all pixel snaps on
• You can see the fractional coverage bug in the gray artifacts at the upper-right edges and corner:

Workarounds are very awkward; you have to overscale by 1 pixel (or disable pixel snapping and drag a fraction of a pixel past the edge). That means snapping is worthless, basically. The bug occurs on many other resolutions as well, but not all. When the resolution is high, the translucent fringe pixel is often as little as 50% covered. It's particularly nasty in high-res projects because you don't notice the fringe unless you zoom way in.

 

scale-snap-bug.afphoto

[m888]

KarlLegion posted a response in the original thread. Here's a copy of his note:

I think it's not related to the pixel alignment because all coordinates are integral from your example. I suspect it's the issue on the image object.

My theory is, image objects are treated as vector objects which have a "Viewbox" bounding the pixels. It seems to me that there are invisible thin transparent edges between the boundary and the pixel. As long as you rescale the object, those edges stretch. I can reproduce it but it only happens in Photo but not Designer. So, it's probably a bug. You can report it in a separate post.

[Old Bruce]

The two sizes (200 and 210) are unimportant. What is important is the scaling up, check using the Info panel in the corner pixels of the new enlarged size and in the centre of the square. Use contrasting colours for the background and the 200px square in order to really see it.

[KarlLegion]

Some notes to add according to my test.

• pixel layers and image layers are affected (vector objects not)
• The fringe disappears once the objects are rescaled to twice its original width/length and beyond

Please correct me for any different findings

[NathanC]

Hi All,

Many thanks for the detailed contributions, i've been able to replicate this and it has now been logged with the developers. 🙂