Image Number 6 for United States Patent #5359674.
Multiresolution (pyramid) filtering is useful in image processing. An IC for implementing a variety of multiresolution filters includes a programmable, symmetric, and separable two-dimensional filter. The input signal to the filter can be an input signal applied to the IC or a combination of two such signals. Circuitry in the IC may be programmed to imply pixel values around the edges of the two-dimensional image signals processed by the filter. The filter provides an output signal as well as each of the unfiltered signals from a tapped delay line of a filter that combines successive lines of the image. The IC also includes an arithmetic and logic unit in which the filtered output signal may be combined with an unfiltered input signal or one of the unfiltered tap signals. If the filter is programmed to produce a Gaussian low-pass filtered image, this image, combined with image data from a center one of the filter taps produces a Laplacian function of the original image.