Colorized +/- difference between images

[anthony]

The operation to find the difference bettween the to images is going to be tricky
but not imposible,

If you just subtract image A from B then the values will be B-A

If A is a larger value it will be clipped at zero. while is B is larger the vaue will
be the right difference. swapping the two images will generate negative difference
and clip the positive differences at zero.

the solution then becomes simple...

Code: Select all

     composite -compose subtract  A  B   blue.png
     composite -compose subtract  B  A   red.png
     convert  red.png  blue.png  -background black  -channel RB -combine  difference.png