Image Enhancement
By subtracting two images of a scene or object taken some time apart, it is possible to detect changes that have occurred over the time interval.
This is useful in motion analysis.
Digital subtraction angiography is a medical imaging technique to image blood vessels in the human body by subtracting an initial x-ray image from a post-contrast-injection x-ray image.
Exact registration of images is essential in both addition andsubtraction of images.