why should i subtract mean of image when searching for position of sub-image in image?

i have tried several times to find position of sub-image inside the bigger image, and i found out that i must substract the mean of the images for it.

i still couldn't understand why.

can someone help please?

Answer 1

[Jalaj Gambhir]

Hi,

I am not sure the complete process that you are following, but subtraction with mean Image is generally done to center the image. It is a common preprocessing step for most Image Processing algorithms.

Hope this helps!