I used the grain effect with a few others to simulate leather texture in an image. When it came time to export, I wanted to export it at half size so I used Export for Web with the 0.5x modifier. Unfortunately, the grain didn't scale with the image so the leather texture ended up way too big. In the end I exported full size and resized in Apple Preview. I'm guessing that this shouldn't happen.
To reproduce (Pixelmator Pro 1.5.5 on macOS 10.15.3):
1. Create an image 1000×1000px.
2. Fill with mid-grey.
3. Apply grain (Effects > Stylise > Grain) and put Intensity and Size to Max (with Option over-ride) so that you can clearly see the grain.
4. File > Export for Web... and switch between 0.5x and 1x. Notice how the grain jumps in size when you select 0.5x
Hope you can reproduce and fix.
(I haven't extensively tested with other effects but saw this happen to the Noise effect, too, so it's not just the Grain effect that is affected)
Is something not working like it should? Let us know.
Hey Stef, thanks for reporting this — you're absolutely right, both the Grain effect and color adjustment seem to have this issue with the 0.5x scale factor while the others appear to be OK. We'll get working on a fix! I can also see that a few other effects are affected, no pun intended.