Local equalization, laplacian sharpening, unsharp mask, and rank masking are all very noise sensitive, because both random speckle and shot noise produce pixels that are different from their local neighborhood. Image noise must be removed before enhancement is attempted, or the visibility of the noise will be increased. This interactive tutorial illustrates the effects of shot or speckle noise on procedures that enhance local contrast in images.

The tutorial initializes with a randomly selected specimen appearing in the Specimen Image window. The Choose A Specimen pull-down menu provides a selection of specimen images, in addition to the initial randomly chosen one. The Noise Type buttons select Speckle or Shot noise to be added to the original image. The Operation buttons select Local Equalization, Laplacian sharpening, an Unsharp Mask, or a Rank Mask as the enhancement procedure.

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