I have about 100 raster (grid) files (in the "ascii grid" format) of drought index. All cover the same area of interest but at different times of year. I need to create images from the grids with exactly same color scheme: index>100 - dark red, index 50-99 - red, index 25-49 orange, index 10-25 yellow, index 0 - 10 white.
I tried to do this in SAGA GIS, but SAGA GIS always automatically generates the color scheme by dividing the full range of values in equal intervals.
Is there any free GIS that you would recommend for doing this type of task? (I have some small experience with bat file or python scripting..)