"Hairline," faint border around PNG exports
Whenever I export anything as a PNG in Illustrator with a transparent background, the PNG result shows up with a strange faint border around it. I've tried a multitude of "solutions" and nothing has worked, leading me to believe that this is a bug.
I'm working on a macOS Catalina 10.15.4, and on the most recent version of illustrator (24.1). My processor is 1.6 GHz Dual-Core Intel Core i5, and graphics—Intel UHD Graphics 617 1536 MB.
(The image I have provided is the exported PNG image of that shape, and I've overlapped it ontop of the pre-export to show the "hairline," faint border around my PNG exports.)
Thomas Theiler
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This is a GPU bug. If you toggle the rendering mode with View > View using CPU — no border will get rendered, the PNG actually does not have it. The problem is known though.
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Denis, I know what you referring to, but I believe it is a completely different problem, but with a matching description. Thomas clearly refers to the GPU artifact for placed PNGs, and you refer to the actually generated and baked artifacts in the PNGs, generated with scale factor other than 100% in Save for Web (and sometimes with 100% also).
Can you please log it as a separate report? -
Denis Rionnet commented
The CPU / GPU view mode doesn't seem to affect the issue on PNG export (File > Export > Save for web).
However, I also noticed:
– "Type Optimized" gives better results than "Art Optimized" (although the issue is originally not type related).
– The issue depends very much on the exact export resolution. In my case, I export 1600x900 artboards to 1920x1080 PNG files, i.e. a 120% ratio, which seems to be the worst case. 110%, 121%, 130%, 150%... do not cause the same grey borders on coloured rectangles. Actually, in some cases, if I just add one single pixel to the export width (1921px rather than 1920), the unwanted grey line disappears. Or sometimes 121% rather than 120%. -
Same on Windows. Only happens when resizing.
Only workaround found: adding a 0px gaussian blur on objects having this issue, but it sucks.