About find shared void of two pictures

Hi,

I’m trying to use imageJ to overlay two pictures and find the shared void area. When i use the merge channel function to make a composite picture 3 from pic 1 and pic 2, it gives me all the void from picture 1 in red and picture 2 in green, and the shared void area in yellow. Then u convert it to black and white 8-bit, which generates pic 4. However, the void (black area in pic 4) are the summation of red, green and yellow. Is there anyway to make the yellow part of pic 3 the only black area in pic 4?

Thanks,
Danny
1.tif (23.7 KB) 2.tif (23.7 KB) 3 4

Hi Danny_Xu, welcome !

Check the command Process>ImageCalculator...

The AND operator will give you the desired result if both images are black/white and inverted (Edit>Invert)