Large Images with multiple layers rendering non-existent lines when rotating at specific Zoom Levels.

The conditions for me to reproduce this bug are highly specific, so I will list them.

  • Painting in Corel Painter 9, 2013, 2015, 2017, 2019.
  • Working on an image larger than 2000x2000
  • With multiple layers.
  • The position of layers are incorrectly rendered on screen, offset by a sub pixel. So that if I'm doing comic style inking, with a color fill on a separate layer, the inks and color fill layer don't line up correctly and mislead their true position. The reason I say this is a rendering issue, is that if the layers are collapsed to canvas, they snap to their true position. Which is different than previously displayed.
  • Then, when zoomed out to specific increments, 10%, 25%, 50%, 75%, and even not zoomed at all, viewing the image at 100%, while also rotating the canvas at 90 degree increments. Vertical and Horizontal transparent lines show up across all layers. They look like single pixel cuts through the layer, revealing the layers underneath. Again, they disappear when the layers are collapsed, they are rendering artifacts.

I suspect it may be a hardware issue, some kind of memory problem, I only have 8 gigs on my laptop and 16 gigs on my desktop. I've reproduced this bug across multiple machines, and different versions of Corel Painter software. The issue becomes more pronounced, with a greater distance of mis-rendering layers, and more lines whenever I open two files simultaneously. Unless I close and reopen just one, the problem persists in its more pronounced state. But if the file I reopen is large enough, it persists regardless.

If you need more hardware information about my systems to pinpoint the issue, I can provide it.

Why have I run into this problem so persistently? There are obviously work-arounds. An artist must work within the limitation of their medium, but these specific bugs have become a constant source of aggravation anyway. So I ink with thicker lines, I zoom 33% and 66% when rotating the canvas. However, the reason I like to use these specific zoom increments, is that they normally display the image much crisper, and with much more accuracy. The rotation tool is most convenient for drawing more precise and comfortable lines from different directions. And similarly with the zoom levels, the 90 degree rotations allow the most crisp rendering of the image. I like to be able to snap back and forth between highly accurate views of my artwork while drawing comic art or doing digital painting. For larger digital paintings I just have to work only on the canvas, and use layers only to save selection masks.