Linear Filtering

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Many useful image processing operations may be implemented by filtering the image with a selected filter. Digital Image Processing defines a large number of smoothing, sharpening, noise reduction, and edge filters. Additional filters may be easily added or designed using the filter design functionality of the package.


BoxFilter, GaussianFilter, and SmoothingFilter are all variants of so-called smoothing filters. They produce a response that is a local (weighted) average of the samples of a signal.

The Savitzky-Golay smoothing filter is an optimal filter that returns the best average value, in the sense of least squares, for each neighborhood of image points. It is a good general-purpose smoothing filter. Here we show the coefficients of a Savitzky-Golay filter of order three and length five.


This loads an example image and computes a smoothed copy using the filter shown above.


Here we display the two images.