[Painter] Weird normal map behavior when using filter.

Udjani

I was following the tutorials on youtube and im facing this problem, when the normal option is activated on the filter effect, the normal map get weird, The tutorial was made with an older version, and the normal option was not avaliable there, but seems like that it gives more details. So, the normal shouldn't be activated? and if is a bug, how can i solve it? 

Yesterday i had this same problem, but it was with a brush. 

Revel

It's because you are filtering the normal color itself (since you placing the filter on to the main layer instead of a mask). You can check your normal map display and see that most probably it's not the natural looking color (blue/purple-ish).

Normal map calculate the vector of the mesh surface using the color so you don't what to filter that (its another reason why you should always use linear space on normal map instead of srgb, like albedo for example).