Why isn't the filter gallery working in cmyk mode?

[B.Jaewon]

I know that filter gallery only works on rgb/8bit, but I was wondering why. Why doesn't filter gallery work on cmyk?

[didiermazier]

I do not know the reason why but here is what you can do :

Convert layer to smart object

Open smart object and convert to RVB 8 bits

The filter gallery is effective

You can even convert the layer of the .psb to as mart object to get a non destructive filtering…

Close the smart object .PSB

Flter applied…