[digital image processing]
In image processing, a computing technique by which the size, colors, shading, and other characteristics of an image are altered. Typically uses an `<n x n>` matrix of weights. The resulting calculation to each output pixel is restricted to the size of the matrix, referred to as a kernel. Filters are used primarily in pixel-based analysis where the value of a center pixel is changed to the mean, sum, or other function of all pixel values within the filter. Image filters move systematically across a raster until each pixel has been processed.