Pedro Côrte-Real wrote:
I was just trying not to waste too much paper. 600 was just a random guess on my part. How many should I aim for for a good profile?
For a well behaved "RGB" printer, somewhere between 600-1000 is good, but it depends on expectations. It's hard to use too many patches for a badly behaved printer. [A badly behaved printer is one in which an even spread of device values does not result in an approximately perceptually even spread of colors.] If you've generated the three 200 point charts independently (ie. they aren't re-prints of each other), and they are all under the same printing conditions, then another thing you could try is to concatenate all the results and generate a profile from that. It may "fill in the gaps" a bit, although it won't be near as good as a deliberately made 600 point chart. You can concatenate using a text editor or spreadsheet program on the .ti3 file. Just make sure that the NUMBER_OF_SETS is set correctly for the total number of points. The SAMPLE_ID and SAMPLE_LOC are ignored by colprof.
I took the -d3 from the docs. I assumed it had to be that because the profile was for RGB not CMYK even though eventually gutenprint is going to convert it into device space. Is this not the case? If it is
Right, but in V1.1.0 -d2 selects "Print RGB", which gives targen a few more clues that it's really a printer, and not a display. [Sorry, not all of the doco has caught up with this change yet, but targen -? indicates this.] Graeme Gill.