1. A method for determining the accuracy of an estimated value for a pixel being generated within a window of pixels, comprising: determining, using a signal processor, a value of each pixel in the window of pixels; computing a mean value for the window of pixels; comparing the determined value of each pixel in the window of pixels with the mean value to determine whether each pixel is less than or greater than the mean value; determining the number of times a pixel having a determined value less than the mean value is horizontally adjacent to a pixel having a determined value greater than the mean value; and generating, using the signal processor, an ambiguity measure proportional to the determined number, wherein the ambiguity measure is used to produce the estimated value for the pixel being generated.