#170: r.colors: make nice random colors like r.watershed --------------------------+------------------------------------------------- Reporter: hamish | Owner: [email protected] Type: enhancement | Status: new Priority: minor | Milestone: 6.4.0 Component: default | Version: svn-develbranch6 Resolution: | Keywords: r.colors --------------------------+------------------------------------------------- Comment (by hamish):
Replying to [comment:2 glynn]: > If I'm reading the code correctly, it creates a set of random > colours, then replaces any dark colours with non-random colours > selected from generated gradients. IOW, it's a fudge which > shouldn't be elevated to a library function. ok. fwiw I'm looking at a r.watershed map with one color as 27:36:70, fairly dark. > If you just want to eliminate dark or saturated colours, this is the core of the wish I suppose, > it would be preferable to add transformation functions to adjust > and/or clip the intensity, saturation and hue, which could then > be applied to any existing colour rule, not just random colours. r.colors -m # for "mute" ? It would be a nice excuse to create proper G_hsv2rgb() and G_rgb2hsv() fns. ie calculate hue angle using real sine/cosine, not just use the hexagon approx to the circle. http://www.mandelbrot-dazibao.com/HSV/HSV.htm I am also a little confused in my r.cpt2grass GMT color scale -> GRASS colr/ rules converter: "value" = 0.0 is white, but is 1.0 black and 0.5 "maximum"? or is 1.0 full-scale color? Some of the GMT rules (/usr/share/gmt/cpt/GMT_topo.cpt) have S all < 0.5 and look washed out with my script unless you do S*=2. And another (GMT_sealand.cpt) has value all = 1.0, and AFAICT that all becomes black? http://article.gmane.org/gmane.comp.gis.grass.user/23635/ http://trac.osgeo.org/grass/browser/grass- addons/raster/r.colors.tools/r.cpt2grass Maybe I just have to elevate my brain sugar and study it again. (eg mixing up S and V and/or HSV and HIS) the wikipedia page on it suggests V=0.0 is white and 1.0 is black. http://en.wikipedia.org/wiki/HSL_and_HSV shrug. but I digress, Hamish -- Ticket URL: <http://trac.osgeo.org/grass/ticket/170#comment:3> GRASS GIS <http://grass.osgeo.org>
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