My command is as follows
gmic cat.jpg split c afre_gui1[1,2] [0],1,1e0,0 append c cut 0,255
Indices 0,1,2 correspond to RGB channels respectively. I am using the R channel because it contains the most info as shown in post #10.
Take 2. Same algorithm but with different ratios and less code. This one doesn’t produce the magenta but neutralizes it. Still doesn’t look quite right.
PS Part of the problem might be neglecting to convert sRGB to linear RGB…