mirror of https://github.com/GNOME/gimp.git
88 lines
3.0 KiB
Plaintext
88 lines
3.0 KiB
Plaintext
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Print plugin for the Gimp. Version 3.0 by Robert Krawitz
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<rlk@alum.mit.edu> based on version 2.0 by Michael Sweet
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<mike@easysw.com>.
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This version has numerous enhancements:
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1) Full support for the Epson Stylus Photo, Photo 700, and Photo EX
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printers, including 6-color printing, 1440x720 dpi resolution, and
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"soft" weave for much faster high quality printing.
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2) Many new controls, including:
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* Output gamma adjustment
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* Contrast
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* Red/green/blue levels
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* Saturation
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* Density
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* Additional scaling options
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3) Improved tonal resolution. Calculations are now done in 16 bit
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rather than 8 bit resolution, which eliminates stair stepping.
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Input levels do not map one to one onto output levels, so in 8 bit
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output resolution multiple input levels will map to a single output
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level. Usually the density range is compressed in the light end of
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the tonal range, so many different input levels will map to one
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output level. Use of 16 bit output resolution avoids this
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undesirable behavior and results in smooth tonal gradations in
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highlights.
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4) Saving of all settings between print jobs.
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This plugin has been optimized for the Epson Stylus Photo EX, since
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that's the printer I own. I am interested in comments on performance
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both with Epson Stylus printers and with others.
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Some tips on tuning the output:
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* Start with the default settings
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* Brightness and density are not the same thing. Density is a purely
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linear adjustment; more density means more ink. Brightness affects
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perceived brightness.
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* Higher gamma values result in brighter images with compressed
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highlights. Lower gamma values are darker, but with better tonal
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range in the highlights.
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* Different brands of ink yield different results. I've found that
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third party inks on Epson printers are generally too cyan. The
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correction for excessive cyan is to add red (or reduce blue and
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green).
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* I've found that what creates good test patterns does not necessarily
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create good photographs. In particular, test patterns often print
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well with gamma of .6 or thereabouts, but that gives washed out
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photographs. Perhaps when I implement a better contrast control
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this can be improved.
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* The contrast control scales polynomially around the midpoint of the
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range. Lower contrast will reduce the contrast in the midtones, but
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increase the contrast in the highlights and shadows. Contrariwise,
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a high contrast value will stretch the scale in midtones,
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compressing the highlights and shadows.
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* There are many combinations of brightness, gamma, and density that
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will create acceptable images. You may find that you want different
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settings for different images.
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* One group of settings you might want to start with is:
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Brightness 110
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Gamma 1.3
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Contrast 80
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Green 94
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Blue 89
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Saturation 1.15
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Density 1.6
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Makefile.standalone enables you to build this plugin as a standalone
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plugin, without reference to a Gimp source tree.
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Enjoy!
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-Robert Krawitz, November 14, 1999
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