In addition to blurring edges and detail when applied to random speckle noise, convolution filters have even greater difficulties when applied to images with shot noise. In these instances, the extreme pixel values are averaged with their neighbors and while the magnitude of the noise is reduced, it is spread out into a larger area that may make it even more visually objectionable. This interactive tutorial illustrates the effects of neighborhood averaging or Gaussian smoothing on shot noise.

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. For a color image, clicking either the Monochrome Noise or the Channel Noise radio buttons determines whether the noise is added independently to each channel to the brightness values only. The Shot Noise Level slider controls the amount of noise that is added. The Choose A Convolution Kernel pull-down menu determines the type of filtering operation that will be performed on the specimen image. The result of the filtering operation appears in the Filtered Image window.

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