Patent ID: 7277592

Claim:
A de-blocking filter for smoothing block edges of decompressed images comprising: a maximum generator for generating a maximum-allowed edge-pixel difference as a function of a quantization parameter, the quantization parameter indicating a degree of compression of an image; a difference generator, receiving pixel components from an edge pair of adjacent pixels in adjacent blocks, for generating an edge-pixel difference; a limiter, receiving the maximum-allowed edge-pixel difference and the edge-pixel difference, for generating a difference term, the difference term being the edge-pixel difference when the edge-pixel difference is less than the maximum-allowed edge-pixel difference, but being the maximum-allowed edge-pixel difference when the edge-pixel difference is larger than the maximum-allowed edge-pixel difference; a fractional difference generator, receiving the difference term from the limiter, for generating a plurality of fractional differences having a decreasing range of values that are fractions of the difference term; and an applicator, receiving pixel components from a current row of pixels that includes the edge pair of adjacent pixels in the adjacent blocks, for adding or subtracting the fractional differences from the fractional difference generator to pixel components for pixels in the current row; wherein successive pixels successively farther from the edge pair of adjacent pixels have successively decreasing fractional differences added or subtracted, whereby edge-pixel differences are smoothed over the current row of pixels.