Abstract: A method of reducing ringing artifacts in image data that has been filtered with a high frequency emphasis filter. For each filtered data value, a local variance is calculated from data values at neighboring filter taps. This variance is compared to a threshold, and if the threshold is exceeded, the filtered data value is limited between local minimum and maximum values. A method of reducing noise, also using the local variance, is also described.

Abstract: According to teachings of the present invention, a system and method for a sharpness filter for picture-smoothing architectures are provided. In one embodiment, the method includes applying a finite impulse response filter to a brightness channel of an image prior to applying a picture-smoothing algorithm to the image, determining a local variance estimate for the image, and varying a gain of the finite impulse response filter based upon the local variance estimate, wherein the finite impulse response filter is an inverse of a filter that approximates the picture-smoothing algorithm.