Superimpose two simmilar images to get WHITE?

[boolean]

Does anyone know how to superimpose (with layers) image A and say image B where the 90 % of these 2 images is absolutely the same, in such way that areas which are the same should become WHITE while remaining 10% should show the differences?

I have tried with positive A and 50% Alfa of NEGATIVE B on layers and I got 90% oaf the area GREY and 10% pretty good difference

Help ASAP

Thanks

Boolean

 

[blueark]

The closest I could come to this is the following:

1: Make sure your file is in RGB mode
2: You have your 2 layers, A underneath and B on top
3: Make a copy of the layer who's 10% you want to see at the end and hide it (say it's called layer C).
4: Set the blending mode in layer B to Difference
5: Merge layers A & B (if C is hidden, you can select Merge Visible)
6: Select the new layer A (background), select all & copy.
7: Make layer C visible again and create a layer mask.
8: In the channels palette, select the layer mask (including the visibility icon, the one that looks like an eye) and paste. Deselect the visibility icon and go back to the layers palette.
9: Change the background layer to white.

There you have it. You'll probably need to play with curves or levels on the layer mask to get the right opacity. If you've a few images to work with, you'll be glad to know that all of this can be made into an action that can be reused as often as you like!