Image differencing is an image processing technique used to determine changes between images. The difference between two images is calculated by finding the difference between each pixel in each image, and generating an image based on the result. For this technique to work, the two images must first be aligned so that corresponding points coincide, and their photometric values must be made compatible, either by careful calibration, or by post-processing (using color mapping). The complexity of the pre-processing needed before differencing varies with the type of image.
Image differencing techniques are commonly used in astronomy to locate objects that fluctuate in brightness or move against the star field.
The Hutchinson metric can be used to "measure of the discrepancy between two images for use in fractal image processing".
Famous quotes containing the word image:
“Let us imagine a number of men in chains and all condemned to death, where some are killed each day in the sight of the others, and those who remain see their own fate in that of their fellows and wait their turn, looking at each other sorrowfully and without hope. It is an image of the condition of man.”
—Blaise Pascal (1623–1662)