Patent ID: 7346226

Claim:
A method of reducing mosquito noise in an image frame of a video signal, the method comprising: examining a window of the image frame, the window including a plurality of pixel values; subtracting a selected one of the pixel values from the pixel values in the window to define a modified window of pixel value differences; computing a local mean value E DC of the pixel value differences in the modified window of pixel value differences; applying a highpass filter to the pixel value differences in the modified window of pixel value differences to generate a reducing value E cb ; computing a weighting coefficient α as a function of a variance of the pixel value differences in the modified window of pixel value differences; computing a weighted sum of the reducing value E cb and the local mean value E DC after multiplication with the weighting factor α to define a mosquito noise reduction value u according to the relation: u=αE cb +(1−α) E DC ; generating a nonlinear function Ψ(u) of the difference between the mosquito noise reduction value u and the local mean value E DC ; computing an artifact attenuation factor λ as a function of a dynamic range measure of the pixel value differences in the modified window of pixel value differences; adding the local mean value E DC to Ψ(u); multiplying the artifact attenuation factor λ by the sum of the local mean value E DC and Ψ(u); and adding the selected one of the pixel values to the product of the artifact attenuation factor λ and the sum of the local mean value E DC and Ψ(u).