A ReShade implementation of three flavours of Kuwahara filtering - based on the article from GPU Pro (2010) - all in one file.
TO-DO: Add convolved gaussian weights.
Install ReShade for any game/application as usual (https://reshade.me/) and then just copy "Kuwahara.fx" into the "reshade-shaders" directory. You can then enable it and tweak its parameters form the in-game menu.