Arithmetic transformation is a class of pixel-by-pixel arithmetic operations performed on one or two images. Included in this class are alpha blending, image combination, image math function, pixel logic operation and background subtraction.
Alpha blending is useful to create transparent effects, which can be used to render glass or liquid objects in computer graphic. Another use of alpha blending is adding visual objects to a background image.
Image simple math include operations such as addition, subtraction, multiplication and averaging, of two images. Simple as they are, these operations can work as important processing tools in many applications. For example, image subtraction can subtract the background from the input image, if the background image is provided. Image division can be useful for detecting the changes between two images or generating ratio images. Averaging can be used for noise reduction, when multiple images are obtained for a stationary scene and each image is contaminated by an additive random noise source.
In math function and pixel logic, the output image is a pixel-to-pixel mapping of the input image. They can be used for extracting, emphasizing or suppressing some features of the image.
Subtract background function is designed for background removal when the background image is not available.
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