[sculptor]

Many thanks for suggestions. Photoshop Elements sadly does't support CMYK. Presumably I need other software.

I guess part of the problem is room lighting and gloomy weather, but those things are facts of life.

Tried using Photoshop (Elements) to make test strips of RGB running from 0 to 255 in white, red, yellow, blue, and printing out on a black background. Most enlightening. The red and yellow strips looked ok, as did the bright end of the white strip (plain paper). The bright end of the blue strip, by comparison, just wasn't really very impressive. The dark ends of the white and blue strips were a dirty brown-back rather than dark versions of white and blue. It is obvious that no amount of fiddling with Photoshop RGB levels will help, because I can't output more than 100% blue (ie more blue than RGB=[0,0,255]), and certainly can't output "negative" amounts of R or G to get rid of the dirty brown black printed for a dark blue such as RGB=[0,0,25].

Perhaps the inks are at fault ? Will look into Epson R800 with pigment inks - thanks Acropolite.

I don't understand the relationship between RGB and CMYK. I understand the physics and the physiogy, and understand the difference between additive and subtractive colour mixing, but not the nuts and bolts of how RGB maps to CMYK, and whether it might be possible thereby to request purer blues than [0,0,255] or [0,0,25] from the printer, or whether the inks really are limiting.