# Image difference and magnitude.

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Hashem Burki on 22 May 2011
I need to take the difference of two images. Such that image1 is a normal image and image2 is a somewhat skewed. I then want to find the magnitude of The difference image (image1-image2) such that i get a singular scalar value. Then i need to take the difference of two other images (image1-image3) in which image3 is more skewed. I then want to find the magnitude of The difference image such that i get a singular scalar value. now i want to compare both values and be able to tell just be looking at the values that which picture is more skewed and which is not.

Walter Roberson on 23 May 2011
Okay, go ahead and give it a try.
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Walter Roberson on 23 May 2011
Define what _you_ mean by "the magnitude of the difference image" "such that I get a singular scalar value", and we'll try to help you program it.
A question for you to consider:
Suppose your image1 is a vector of 255 zero's, and suppose image2 is a vector of 255 one's, and suppose image3 is a vector of 254 zeros and a single 255. Now, should the difference image magnitude between image1 and image2 be the same as the difference image magnitude between image1 and image3, seeing as the sum of the differences (255 * 1) and (254*0 + 1*255) are the same ?