1. An image noise reduction filter, comprising: a differencing block that computes absolute values of differences between a plurality of metrics of a target pixel X and a plurality of neighboring pixels in a processing window, and that determines a minimum computed difference and a maximum computed difference selected from among the absolute values of differences between the metrics of the target pixel X and the plurality of neighboring pixels in the processing window; and a new pixel value generator, coupled to the differencing block, that generates a replacement value for the target pixel based on a weighted average of the absolute values of degrees of similarity between the target pixel X and the plurality of neighboring pixels.