PNG exports break RGB channels

Ramiro,

What operating system are you using?

Super PNG is not working how?

No, in that case it fills all the transparent pixels with black.

The bug isn't introduced by opening, it's introduced when the PNG file is saved out directly from a masked layer.  When I bake that saved PNG in our engine, I see the white pixels introduced around the perimeter of the RGB.  

The only way I've found to save the PNG with the RGB intact is to use SuperPNG with an opaque RGB and a separately defined Alpha channel (not a layer mask).  In that case, SuperPNG allows you to stipulate the Alpha channel for the transparency source, and it saves without changing the RGB data.

System Info:

Adobe Photoshop Version: 21.0.3 20200115.r.91 2020/01/15: 21f283574f6 x64
Operating System: Windows 10 64-bit
Version: 10 or greater 10.0.18362.329

Well...that's not very encouraging.  I guess I won't hold my breath. 😛

Dave, your answer is great for identifying the problem, but it doesn't offer a solution to the actual problem.  I'm having a similar issue as goosezilla, and although Superpng does offer a workaround, it would be SO MUCH BETTER if Photoshop just did the right thing from the start.

Here's an example:  I start with a simple shield icon with well defined RGB layer data and a layer mask for transparency:

As you can see all the RGB data is solid purple.

After saving as a PNG and reopening I get this:

Photoshop has filled in the RGB data around the edges with garbage data, in this case white.  This is what it looks like with the alpha mask overlayed on the new RGB data.

This happens whether I use Save As or Export, and it also happens with Superpng IF I try to save it out directly from a masked layer.  (Superpng does do the right thing if you have an opaque layer and put the mask in an Alpha Channel, which is OK but it adds more steps to my workflow).

I'm a game artist and we often need to maintain precise control over all for channels, RGBA.  I can't just have Photoshop randomly changing "transparent" RGB data on me.

I would LOVE it if Adobe would fix this and make PNG saving preserve RGB data.  (I don't really see any good reason why it doesn't?)  Alternately, if someone can point me to a PNG plugin that preserves RGB data when saving from a masked layer, that would be great too.

Thanks,

Matt