greyscale conversion and posterization

First post here, and a thanks for this wonderfull sw.
I create some 8bit, greyscale raster maps from geotiffs, then process them with an array package, creating a new map with different levels of grey. These maps predict the Risk of disease infestation in agricultural areas.

I then use “posterize” to have 10 classes, making the maps easier to analyze.

I use this command, after RTM:
gmic png_in.png fx_posterize 67,19,0.85,12,0,40,10,0 -output png_out.png

The maps come out really nice, in general, and I create a 10 level legend for visualizing Risk on the map.

What I want to try now, is to convert/posterize my 8bit grey to 10 shades only between red and green. Red “High Risk” <—> Green “Low Risk”.

I have not figured this out yet,


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Hi @olNick and welcome!

I am not especially good at these things, but I believe
that Gimp|Colormap, and/or G’mic|Colormap could be
of use to you.

Have fun!
Claes in Lund, Sweden

Hi @olNick, I think you could do all of this in the R statistical software, from the geoTIFF creation (or reading) to generating the color map according to the scale you want. Packages such as rgdal, raster and ggplot2 come to my mind for this.

I’m already using gdal for most of the translations.
Just hoping that gmic could be utilized here to add the colors. This is the last step in the processing pipeline…