Patent ID: 7194143
Filing Date: 2007-03-20
Classification: G06T,H04N

Abstract:
1. A method of enhancing a digital image bearing artifacts of image compression, the artifacts comprising at least one of blocking and ringing, the method comprising: (a) forming a constraint matrix for a digital image bearing artifacts of image compression, the constraint matrix based on at least one of: (b) encoding information of the digital image bearing artifacts with transform coefficients of the digital image, wherein the encoding is accomplished with a transform; (c) applying a first filter to the digital image and forming a first temporary data matrix containing data of the first filtered digital image, the first filter including at least one of a local median filter and a morphological operator different from the local median filter; (d) filtering the first temporary data matrix with a second filter to form a second temporary data matrix containing data of the twice filtered first temporary matrix, the second filter including at least one of a Fourier multiplier filter, a convolution filter, and a wavelet filter; (e) multiplying the second temporary data matrix by a predetermined step size parameter; (f) altering coefficients of the multiplied second temporary data matrix having additions to respective transform coefficients of the digital image which violate a predetermined constraint as indicated by a comparison of known data with the constraint matrix; (g) adding altered coefficients of the multiplied second temporary data matrix to corresponding coefficients of the digital image input; (h) inverse-transforming the altered coefficients of the matrix resulting from step (g) to form a new enhanced representation of the digital image input; and (i) repeating (b)–(h) a predetermined number of times applying these steps each time to the newly enhanced representation of the digital image input, whereby the visual quality of the newly enhanced representation of the digital image is enhanced with respect to the digital image containing artifacts of image compression for at least one of display and further electronic processing.