Spacial Deblocking Method Using Limited Edge Differences Only to Linearly Correct Blocking Artifact

A computer-implemented method for smoothing blocking artifacts comprising:

• receiving a series of pixels that cross a block boundary, the series comprising in sequence a first pixel, a second pixel, a third pixel, a fourth pixel, a fifth pixel, a sixth pixel, and a seventh pixel;
• wherein the first, second, third, and fourth pixels are in a first block and the fifth, sixth, and seventh pixels are in a second block;
• wherein the fourth pixel and the fifth pixel comprise edge pixels in the series of pixels;
• generating a limit value from a quantization parameter that indicates a degree of compression of pixels in the first block;
• generating a negated limit value from the limit value;
• generating an edge difference value;
• selecting the edge difference value as a limited difference when the edge difference value is positive and less than the limit value;
• selecting the edge difference value as the limited difference when the edge difference value is negative and greater than the negated limit value;
• selecting the limit value as the limited difference when the edge difference value is positive and greater than the limit value;
• selecting the negated limit value as the limited difference when the edge difference value is negative and less than the negated limit value;
• generating fractional differences from the limited difference;
• and
• subtracting the limited difference from a pixel to smooth the pixel.

A computer-program product comprising:

• a computer-usable medium having computer-readable program code means embodied therein for smoothing block artifacts produced during video compression, the computer-readable program code means in the computer-program product comprising:
• input means for receiving a series of pixels de-compressed from a motion-picture-experts group (MPEG) compressed video stream, wherein a current series of pixels comprises at least five pixels;
• maximum means 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;
• difference generator means, receiving pixel components from an edge pair of adjacent pixels in adjacent blocks, for generating an edge-pixel difference;
• limiter means, 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 between the maximum-allowed edge-pixel difference or a negation of the maximum-allowed edge-pixel difference, but being the maximum-allowed edge-pixel difference when the edge-pixel difference exceeds than the maximum-allowed edge-pixel difference or the negation of the maximum-allowed edge-pixel difference;
• and
• fractional difference generator means, receiving the difference term from the limiter means, for generating a plurality of fractional differences having a decreasing range of values that are fractions of the difference term.