I've put a new version of the print plugin on my web site -- this version includes two new features: a saturation control, and a "linear" scale mode. The linear mode is a hack to try to improve output to the Stylus Photo EX; the saturation control applies to everything. It's probably worth experimenting with. It's an attempt to get better tonality. Getting the tonal range correct is *hard*. It's on my web site, as usual, at http://www.tiac.net/users/rlk/print.tar.gz. It's still not reachable from my home page there (I'm rather embarrassed at how cheesy that page is, and I need to redo it from scratch one of these days). For the Epson Stylus Photo folks, the settings I'm using now are: brightness 106 gamma 0.59 contrast/red/green/blue: 100 saturation: 1.5-2.5 I suspect a slightly larger value for gamma (0.7) might work better, with brightness around 110-120 and saturation in the 2-3 range. However, I'm getting tired of running through ink cartridges, and my wife's getting tired of me "obsessing" in the basement. I'm also being a rather disloyal Red Sox fan :-) Varying the RGB balance even slightly tends to throw things off, but it's possible that a slight decrease in cyan (increase in red) might help a bit. With a third party ink cartridge I used once, though, it was necessary to reduce the green a bit. The Stylus Photo EX is the best supported printer in the plugin right now (no surprise, since it's what I have). It supports full 6-color mode (CMYKcm -- light cyan and light magenta), and it computes everything in 16 bits rather than 8 (this avoids a lot of quantization problems in the light tones). There are still plenty of things left to do here: 1) Support the rest of the printers (other Epson printers, PCL, and PostScript) in 16-bit mode (this shouldn't be hard; the infrastructure is already in place). 2) The Epson driver uses MicroWeave mode in high resolution (720 dpi). This isn't really optimal; it's very slow and it introduces a lot of micro-banding. There are supposedly other ways of doing it. I've been trying to read the GhostScript code to figure out how to do it, but I haven't made much progress. The non-MicroWeave method also allows 1440x720 printing (to the extent that the printer really does it, which is questionable). 3) Better separation of the rendering from the I/O. Currently the individual print drivers work by asking the rendering code to generate a line of output for each line of input, and send that line to the printer. This limits the available dithering algorithms, and makes it hard to implement (2). I'm thinking of a dataflow architecture whereby each line of input is passed to the rendering engine, which in turn feeds lines of output to the printing engine. 4) Do something, SOMETHING, to improve the tonal range! I can get good tonality in some parts of the scale, at the price of having problems elsewhere. For example, some settings give me good highlights and dark midtones, but poor light midtones and dark areas. This stuff is really dependent upon the particular characteristics of the inks and paper. 5) Better dithering algorithms, anyone? -- Robert Krawitz <rlk@xxxxxxxxxxxx> http://www.tiac.net/users/rlk/ Tall Clubs International -- http://www.tall.org/ or 1-888-IM-TALL-2 Member of the League for Programming Freedom -- mail lpf@xxxxxxxxxxxx "Linux doesn't dictate how I work, I dictate how Linux works." --Eric Crampton
