[GRASS-dev] [GRASS GIS] #3110: i.colors.enhance or r.colors: add Gamma correction parameter to improve brightness

[GRASS GIS]

#3110: i.colors.enhance or r.colors: add Gamma correction parameter to improve
brightness
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 Reporter:  neteler                            |      Owner:  grass-dev@…
     Type:  enhancement                        |     Status:  new
 Priority:  normal                             |  Milestone:  7.2.0
Component:  Imagery                            |    Version:  svn-
                                               |  releasebranch72
 Keywords:  i.colors.enhance, r.colors, gamma  |        CPU:  Unspecified
 Platform:  Unspecified                        |
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 Sometimes color composites of satellite data are very dark. A common
 solution is "Gamma correction"
 (https://en.wikipedia.org/wiki/Gamma_correction) which brightens an image
 while keeping colors intact.

 While I would like to see a gamma=... parameter in i.colors.enhance, I
 guess that it needs to be added to r.colors.

 Some code:
  * https://github.com/imagico/gdal-py/blob/master/ls2rgb.py (uses numpy)
  * r7436 brought some gamma support to r.in.png but it is not quite clear
 to me what it does. At least it is in C.

 Maybe it is not complicated to add that?

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Ticket URL: <https://trac.osgeo.org/grass/ticket/3110>
GRASS GIS <https://grass.osgeo.org>