MODIFIED WALLIS FILTER FOR IMPROVING THE LOCAL CONTRAST OF GIS RELATED IMAGES

摘要

Disclosed herein is a method and system for performing adaptive local contrast enhancement for an image by using a linear complexity algorithm for Wallis filter. For an input image, the standard deviation and mean are computed for the first pixel in the image. The computed standard deviation and mean of the first pixel are re-used to calculate the standard deviation and mean for the nearest pixels. So, the standard deviation and mean for each pixel in the image are based on the computed standard deviation and mean of at least one other pixel in the image.

主权项

1. A method for enhancing local contrast of an image in a GIS (Geographic Information System) application, the method comprising
computing column-wise sum for all pixels in the 0th row up to extent of a Wallis window for the 0th row; storing the computed column-wise in memodata1; computing column-wise sum of squares for all pixels in the 0th row up to extent of the Wallis window for the 0th row; storing the computed column-wise in memodata2; computing new pixel colours of the 0th row using horizontal memoization; computing column-wise sum for all pixels in next row incrementally, on incrementing the row; computing column-wise sum of squares for all pixels in next row incrementally, on incrementing the row; and computing new pixel colours of each row using horizontal memoization, till all rows are completed.