10.2.2. Gamma, dotsizes, etc.

10.2.2. Gamma, dotsizes, etc.

Most non-laser printers suffer from the fact that their dots are rather large. This results in pictures coming out too dark. If you experience this problem with an otherwise untunable driver, you could use your own transfer function. Simply create the following file in the ghostscript lib-dir and add its name to the gs call just before the actual file. You may need to tweak the actual values to fit your printer. Lower values result in a brighter print. Especially if your driver uses a Floyd-Steinberg algorithm to rasterize colors, lower values ( 0.2 - 0.15 ) are probably a good choice.

%! %transfer functions for cyan magenta yellow black {0.3 exp} {0.3 exp} {0.3 exp} {0.3 exp} setcolortransfer

It is also possible to mend printers that have some kind of color fault by tweaking these values. If you do that kind of thing, I recommend using the filecolorcir.ps, that comes with ghostscript (in the examples/ subdirectory), as a test page.

For many of the newer color inkjet drivers, there are command-line options, or different upp driver files, which implement gamma and other changes to adapt the printer to different paper types. You should look into this before playing with Postscript to fix things.