If your original file is 4 col the gamut is already smaller than a 6 col CMYKOG gamut or similar so you're not really going to add anything to the file. If you are converting RGB then 6 color is works well.
If your original file is 4 col the gamut is already smaller than a 6 col CMYKOG gamut or similar so you're not really going to add anything to the file. If you are converting RGB then 6 color is works well.