Quote Originally Posted by mhulsman View Post
For VC paper you need a combination of blue or green light or a combination of both.
Grade 5 needs the royal blue led in combination with an UV led, as I read here on apug.
For graded paper you need blue light.
For color you need YMC.
It appears for VC and graded papers all is more difficult , than I thought...
But I print B&W images on classical barit paper, without use of filters. And I wish to have an opportunity the print of colour images in my old enlarger. This problem is slightly easier.

For colour I require YMC if I "isolate" necessary colours from white (substractive method). I require RGB if I "collect" white (additive method). In Fuji Frontier and similar systems use RGB. For this reason modern photographic papers are adapted under frequencies of LED. It also has pushed me on idea to use LED for the print in colour.