Method and apparatus for calculating an SSD and encoding a video signal

A method for calculating the sum of squared differences between an original block S and a reconstructed block R of image or video data, the method comprising the steps of:

• (a) computing with a processor a predicted block P corresponding to the original block S, using inter or intra frame prediction,
• (b) calculating with the processor a residual block D from the original block S and the predicted block P, said residual block D having a plurality of coefficients,
• (c) applying with the processor an image transform to the coefficients of the residual block D so as to obtain a transformed residual block F, said transformed residual block having a plurality of coefficients,
• (d) finding with the processor the coefficients of a first matrix {circumflex over (F)}, said first matrix being an inverse quantized transform of said residual block,
• wherein finding the coefficients comprises iteratively comparing the absolute value of each coefficient of the first matrix to boundaries quantization sub-zones in a look up table, said boundaries of quantization sub-zones having progressively higher quantization point values, until said absolute value of said coefficient is lower than a quantization sub-zone boundary, and
• (e) computing with the processor the sum of squared differences between said transformed residual block F and said first matrix {circumflex over (F)}.

A system for calculating the sum of squared differences between an original block S and a reconstructed block R of image or video data;

• the system comprising:
• a) a processor having a predicting module for predicting a predicted block P, corresponding to an original block of data S, by using inter or intra prediction,
• b) the processor also having a residual block defining module for calculating a residual block D, which is the difference between said predicted block P and said original block S,
• c) the processor further having a transform module for performing an integer image transform on said residual block D to obtain a transformed residual block F* having a plurality of co-efficients f*ij,
• d) the processor still further having an inverse quantization module for finding a plurality of coefficients {circumflex over (f)}*ij , the coefficients {circumflex over (f)}*ij being defined by the equation {circumflex over (f)}ij=Q−1(Q(f*ij)), where Q is an operator which performs quantizing and Q−1 is the inverse of the Q operator,
• wherein the inverse quantization module finds the coefficients by iteratively comparing the absolute value of each coefficient f*ij of the transformed residual block to boundaries quantization sub-zones in a look up table, said boundaries of quantization sub-zones having progressively higher quantization point values, until said absolute value of said coefficient is lower than a quantization sub-zone boundary, and
• e) the processor still further having a difference function computing module for computing a sum of squared differences between f*ij and {circumflex over (f)}*ij.

A non-transitory computer readable medium containing executable instructions stored thereon which, when executed, perform the following steps:

• (a) computing a predicted block P corresponding to the original block S, using inter or intra frame prediction,
• (b) calculating a residual block D from the original block S and the predicted block P, said residual block D having a plurality of coefficients
• (c) applying an integer image transform to the coefficients of the residual block D so as to obtain a transformed residual block F*, said transformed residual block having a plurality of coefficients f*ij
• (d) finding a plurality of coefficients {circumflex over (f)}*ij, the coefficients {circumflex over (f)}*ij being defined by the equation {circumflex over (f)}*ij=Q−1(Q(f*ij)), where Q is an operator which performs quantizing and Q−1 is the inverse of the Q operator,
• wherein finding the coefficients comprises iteratively comparing the absolute value of each coefficient f*ij of the transformed residual block to boundaries quantization sub-zones in a look up table, said boundaries of quantization sub-zones having progressively higher quantization point values, until said absolute value of said coefficient is lower than a quantization sub-zone boundary, and
• (e) computing a sum of squared differences between f*ij and {circumflex over (f)}*ij.