g'mic commandline

I want to know as I can apply an effect on another effect…

gmic sample cat sample apples +patchmatch[0] [1],64,64,1,1,1 fx_posterize[2] 800,0,0,4,64,0,0,0,50,50 +warp[-2] [-1]

But the effect fx_posterize does not apply on the previous effect…
I wish patchmatch+posterize and afterwards do warp

Here, you are applying fx_posterize on the correspondence field generated by patchmatch. Is it really what you want to do ?
fx_posterize[2] should be maybe replaced by fx_posterize[1] instead, just a guess.

I wish to simplify to 4 colours mask it generated by patchmatch

It seems me that I understood it…

2018-12-01-211349_1360x256_scrot
gmic a.png b.png +fx_posterize[0] 800,0,0,16,32,0,0,0,50,50 +fx_posterize[1] 800,0,0,16,32,0,0,0,50,50 +patchmatch[2] [3],64,64,1,100,0 +warp[1] [4]

I attain an interpolation of images

and… aproximate of color…

2018-12-01-214733_1360x256_scrot
gmic a.png b.png +fx_posterize[0] 800,0,0,16,32,0,0,0,50,50 +fx_posterize[1] 800,0,0,16,32,0,0,0,50,50 +patchmatch[2] [3],64,64,1,100,0 c.png +warp[5] [4]

I have to delete the noise by bit plane