Image differencing
Encyclopedia
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 image
s for use in fractal
image processing
".
Image processing
In electrical engineering and computer science, image processing is any form of signal processing for which the input is an image, such as a photograph or video frame; the output of image processing may be either an image or, a set of characteristics or parameters related to the image...
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
Photometry (optics)
Photometry is the science of the measurement of light, in terms of its perceived brightness to the human eye. It is distinct from radiometry, which is the science of measurement of radiant energy in terms of absolute power; rather, in photometry, the radiant power at each wavelength is weighted by...
values must be made compatible, either by careful calibration, or by post-processing (using color mapping
Color mapping
Color mapping is a function that maps the colors of one image to the colors of another image. A color mapping may be referred to as the algorithm that results in the mapping function or the algorithm that transforms the image colors...
). The complexity of the pre-processing needed before differencing varies with the type of image.
Image differencing techniques are commonly used in astronomy
Astronomy
Astronomy is a natural science that deals with the study of celestial objects and phenomena that originate outside the atmosphere of Earth...
to locate objects that fluctuate in brightness or move against the star field.
The Hutchinson metric
Hutchinson metric
In mathematics, the Hutchinson metric is a function which measures "the discrepancy between two images for use in fractal image processing" and "can also be applied to describe the similarity between DNA sequences expressed as real or complex genomic signals."-Formal definition:Consider only...
can be used to "measure of the discrepancy between two image
Image
An image is an artifact, for example a two-dimensional picture, that has a similar appearance to some subject—usually a physical object or a person.-Characteristics:...
s for use in fractal
Fractal
A fractal has been defined as "a rough or fragmented geometric shape that can be split into parts, each of which is a reduced-size copy of the whole," a property called self-similarity...
image processing
Image processing
In electrical engineering and computer science, image processing is any form of signal processing for which the input is an image, such as a photograph or video frame; the output of image processing may be either an image or, a set of characteristics or parameters related to the image...
".
External links
- Sussex Computer Vision webpage: Use of motion information in computer vision