Patent ID: 6163621
Filing Date: 2000-12-19
Classification: G06K

Abstract:
An image processing method comprising:(a) selecting a window that is first in a series of windows, wherein each window in the series covers an area in an image and overlaps an immediately preceding window in the series, the windows collectively covering a portion of the image that is larger than any individual one of the areas;(b) determining a histogram of pixel values for pixels in the selected window;(c) determining a transform function for the selected window from the histogram for the selected window;(d) applying the transform function for the selected window to pixel values corresponding to at least one of the pixels of the selected window, wherein applying the transform function to a pixel value generates an equalized value;(e) determining whether the selected window is last in the series;(f) selecting a window that is next in the series and repeating steps (b) through (f), if the selected window is not the last; and(g) displaying the image, if the selected window is the last, wherein visual appearance of pixels in the image as displayed varies according to the equalized values obtained in step (d), wherein applying the transform function comprises:low-pass-filtering brightness values for pixels in the selected window to generate filtered brightness values; andapplying the transform function to the filtered brightness values.