Michael Schulz wrote: > I would like to ask you and other people who have already experiences using > targen to create test target values for proofing purposes in practice, which > targen options you normally use. For RGB printers: At first, I check the printer linearity. It may be checked by preliminary profile after printing several hundred default OFPS-spreaded patches. For example: targen -v -d3 -f384 Preliminary printtarg... chartread... colprof -v Preliminary xicclu -ir -pl -fif -b -g Preliminary.icc If the curves on plot a quate straight from they start to they end, the printer is OK. If the curves are significantly devate from straight line between start and end (they may be like a gamma-curves), the printer is non-linear. If the printer is linearized well, I use only default OFPS. It gives the best results in the case. For example "targen -v -d3 -w -f2304 RGBTarget". If the printer is rather nonlinear, I generate target with "perceptual space body centered cubic grid spread" and with preliminary profile. Example: targen -v -d3 -f2304 -c"Preliminary.icc" -A0.95 -I -w RGBTarget For CMYK printers: The "perceptual space body centered cubic grid spread" is computing on inverted profile table. The inverted profile table is depend of black generation selected. But black generation may be computed only on OFPS or "device space body centered cubic grid spread" data. So it is necessary to print OFPS (the best way) or "device space body centered cubic grid spread" target in any case. When the desired black generation selected and normal profile is built, the additional black-generation-depended target may be printed with "perceptual space body centered cubic grid spread". The advantage of perceptual space spreaded target (based on normal profile) will be the patch placement only by selected black generation, not in all device space. Being combined with previous *.ti3 data it may significant improve the next profile quality (with the same black generation) exact in needed device space areas. > I'm talking about the default option (OFPS) - with the result of mostly dark > patches, the -R option which gives patches with a perceptual space > distribution and the -c option using a previous profile. OFPS, -r and -i will produce the close results. They generally dark because of subtractive CMYK print principle. The device space spread will produce many ink combinations and many of combinations really must be dark. It is necessary to print all of device space combinations for correct black generation computing. The one of a problems may be the printer linearity problem. Try to build preliminary profile (about 600 patches) and evaluate CMY linearity with zero and default black generation: xicclu -ir -fif -pl -b -g -kz Preliminary.icc xicclu -ir -fif -pl -b -g -kr Preliminary.icc Alalyze the graphs and conclude if the printer linear. It may be very important. In several non-linear cases the targets with OFPS may be extremely dark and even they reading by instrument may became a problem. The instrument may don't distinct the margins between patches on such targets. So the best results will be with linearized printer. Good Luck!