#1071: histogram equalized color rules for raster takes inordinately long to display -------------------------+-------------------------------------------------- Reporter: isaacullah | Owner: [email protected] Type: defect | Status: new Priority: major | Milestone: 6.4.0 Component: Display | Version: 6.4.0 RCs Resolution: | Keywords: histogram equalization, display, r.colors Platform: Linux | Cpu: Unspecified -------------------------+-------------------------------------------------- Comment (by glynn):
Replying to [ticket:1071 isaacullah]: > Recently, I have discovered that displaying a map that has been recolored using the histogram equalization option (-e) in r.color takes much much much longer than displaying the same map colored without the histogram equalization option. With a histogram equalized raster, every redisplay takes about 5 minutes, If you use -e on an integer map, it will create one rule for each value which occurs in the map, which can result in an excessively large colour table. I'm sure that this very issue has been addressed before, but I don't remember the details. The quick fix would be to use the same code as for floating point (which just splits the range into 1000 bins, and always generates 1000 rules). A better fix is to coalesce a run with a constant colour into a single rule. -- Ticket URL: <http://trac.osgeo.org/grass/ticket/1071#comment:1> GRASS GIS <http://grass.osgeo.org>
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