I recently got matplotlib working on OSX (only agg so far) and am now trying to create a picture with two overlayed images so that only a certain range of values of the top-most figure are blended with the bottom one.
The first image would be plotted with the gray palette:
The second image would be in colors:
I would like to 'threshold' the top figure so that only values, say, greater than 30 are plotted with 'hot' colors and elsewhere the gray im_bottom is shown (without blending it with the colors of im_top).
I was hoping that I could do something easy like this:
How to do this?
Do I have to combine the RGB values of the two images 'manually'?