The gradient effect is caused because 3DGS takes perfectly good 24 bit textures, and munts them down into horrible 16bit ones when it adds them to the compiled map. Bluring the source image will only make it worse.

WED used to show the banding untill they upgraded it to use 24 bit textures loaded from a folder, unfortunatly, the compile process takes those and converts them into efectivly a 16bit wad file encapsulated in the map.

Its the single most annoying aspect of the engine for me, and the sooner we get true 24 bit textures, the better. (also kind of makes a mockery of saying its a 32 bit renderer... "Technically" its a 32 bit renderer.... visually its not in my opinion.

So, to answer your question, there sadly isnt a lot you can do, except start hounding conitec to make 24bit textures a reality.

Regards

Tone