I was trying to do the same thing yesterday...multiple .png's with transparent backgrounds on the same part (an interactive button).
The artwork came from Illustrator, so I tried increasing the resolution to 600ppi and even re-saving in Photoshop to no success.
Ultimately, I had to fire up Maxwell to get it done, but will circle back and let you know if I make any progress because I really want to use visualize more.
I tried a quick test here and I'm not seeing the same general issue. I created a basic transparent background, decal image, in photoshop and I don't see artifacts behind the transparent area as you've shown. I tried both Fast and Accurate.
- Would it be possible to share one of the decal images for us to try out here? (You can PM me if you like)
- Also, it could have something odd to do with the underlying appearance...perhaps you can share that too?
- What version of Visualize are you using and do you see the same thing in Fast and Accurate modes?
I took some time to try some different options to see if I could improve the alpha ghosting. It looks like the substrate material affects the label. However, I did find that exporting as a TIF gave better results.
In this image, the big power icon is a PNG, the small TIF, and the white is a PSD (didn't acknowledge transparency at all) - over a "Soft Touch Black" material:
In this image the material was changed to "Smooth Black":
I'll continue to try to improve my workflow, but I'm wondering if the normal map causes interference with the alpha?
The second image, small power icon is perfect. Looks really crisp. I will mess around with the settings.
If you drop the roughness to 0 of the base appearance with a normal map, the decal transparency ghosting goes away. In fact, the higher roughness values negate the normal map's effect.
At least, on the work I'm doing - YMMV.
Hope that helps on your end!