Orquid "Phoenix"

Orquid "Phoenix"

by ceinmart

submit your photo


Hall of Fame
View past winners from this year

Please participate in Meta
and help us grow.

Take the 2-minute tour ×
Photography Stack Exchange is a question and answer site for professional, enthusiast and amateur photographers. It's 100% free, no registration required.

I have two images that are the same, except that one has an adjustment in its brightness.

Is there a way to compute the difference of these images in Photoshop somehow to see what has changed from one image to another?

Image 1:

original

Image 2 (with brightness adjustment):

with brightness adjustment

share|improve this question
    
What exactly are you looking for as the output? A map of the pixels that have changed? A numeric value representing the amount of change (perhaps in "stops"?) Or something else? What do you want to do with this information once you have it? –  mattdm Oct 6 '13 at 18:57
    
@mattdm I want to the brightness factor that transforms the one into the other image. –  confile Oct 6 '13 at 20:15
add comment

1 Answer

If you layer those in Photoshop and use subtract or difference blend modes, you'll end up with a result that should show the relative difference of each pixel.

Use that result to create a mask (Image > Apply Image, target layer mask)

Then starting with the first image, add an exposure adjustment layer, and use the above mask - I would expect you'd get something close to the second image.

share|improve this answer
add comment

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.