rotated normal map png in photoshop, artifacts in edges?

if i duplicate normal map png image file, rotate it 90 degrees inside photoshop,
then i get those yellow lines.. whats happening?



(same import settings)

 

Can you post the original png normal maps?

 

this one,

 

I was not able to reproduce it initially. So there's nothing obviously wrong in Unity's handling. Tried 2019.2 and 2020.3.


I suspected the problem is the texture has alpha, and Photoshop's default PNG handling is to kill the data in the areas that are fully transparent. It's not a problem for the middle bands because it replaces those areas with a solid color value from the areas around it. But at the edge of the texture it's going to replace the RGB color with solid white. Putting that through the normal map packing & unpacking where the Z (blue) is thrown away and reconstructed gets you that yellow color.


The short version is, never use Photoshop's default PNG file handling. Use SuperPNG and make sure you open the file with the alpha as a separate channel.
https://www.fnordware.com/superpng/

 

ok must be those then, thanks for the info! (also yeah, rotation wasn't important here, just saving it out causes it)



tried all kind of combinations of loading / saving (superpng also) but didn't make much difference,
i guess will have to rotate the model UV map instead of this texture..

 

You need SuperPNG, and you need to read the instructions that come with it.

Mainly, hold down shift when opening to get the options dialog and change it to open transparency as a separate channel. And when you save do the same but make sure clear transparency isn't on.

 

aah! well that was too easy.. : D