If you want to use BIMP on separate images
Set the FG/BG to the required colors
Set the Gradient to FG to BG (Hardedge)
In BIMP Add Other Gimp Procedure and search for plug-in-gradmap
Add the images, set the output folder
This is the equivalent of Colors -> Map -> Gradient Map
Set the FG/BG to the required colors
Set the Gradient to FG to BG (Hardedge)
In BIMP Add Other Gimp Procedure and search for plug-in-gradmap
Add the images, set the output folder
This is the equivalent of Colors -> Map -> Gradient Map