merge two images using a third as selection

Posted by perspixe on Sep 19, 2014; 9:19am
URL: http://imagej.273.s1.nabble.com/merge-two-images-using-a-third-as-selection-tp5009696.html

Hello
I have two 32bits images of same size (6000 pixels square). I have a third of the same size that is an 8bits with a black area not to be selected and a white area that is the selection.
I want to copy the area from one 32 bits image based on the selection onto the same position of the other 32bits image, replacing pixels.
I have been trying to do this for some time and decided to finally ask.
I am conscious this is probably a basic procedure but still has difficulties doing it.
Thank you all.