Harmonic quantizer scale
First Claim
1. A method of coding/decoding digital media, comprising:
- applying forward or reverse operations of a transform on blocks of digital media data;
applying forward or reverse quantization to transform coefficients of the digital media data based on a quantization parameter chosen from a harmonic quantizer scale, wherein the quantization parameter is derived from an integer-valued index i, and a constant value c, as follows;
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Abstract
A digital media encoder/decoder performs quantization/dequantization based on quantization parameters taken from a harmonic quantizer scale. The harmonic quantizer scale can include a normal portion consisting of quantization parameter values harmonically-related as simple fractions of each other, and a denormal portion of quantizers having a linear or other relation. The encoder/decoder further supports a scaled quantizer mode where quantization is performed based on the quantization parameter as scaled by a fractional value. A compressed domain contrast adjustment is effected by adjusting the quantization parameters in the compressed bitstream, without having to adjust and recode the digital media data in the compressed bitstream.
344 Citations
19 Claims
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1. A method of coding/decoding digital media, comprising:
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applying forward or reverse operations of a transform on blocks of digital media data; applying forward or reverse quantization to transform coefficients of the digital media data based on a quantization parameter chosen from a harmonic quantizer scale, wherein the quantization parameter is derived from an integer-valued index i, and a constant value c, as follows; - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A computer-readable storage having instructions thereon, which are not consisting of a signal, for executing a method comprising:
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receiving digital media data; applying forward or reverse quantization to transform coefficients of the digital media data to quantized transform coefficients based on a quantization parameter chosen from a harmonic quantizer scale, wherein the quantization parameter is derived from an integer-valued index i, and a constant value c, as follows; - View Dependent Claims (9, 10, 11, 12, 13, 14, 15, 16, 17, 18)
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19. At least one program-storing device having program code stored thereon, which is not consisting of a signal, for causing a digital media processing device to perform a method of decoding digital media data according to a codec, the method comprising:
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decoding a quantizer symbol from a compressed bitstream representing a quantization parameter chosen from a harmonic quantizer scale for at least a portion of digital media data in the compressed bitstream; decoding transform coefficients of the digital media data portion in the compressed bitstream; dequantizing the decoded transform coefficients based on the quantization parameter; and performing an inverse transform to reconstruct digital media; wherein the quantizer symbol is an integer-valued index i that represents the quantization parameter according to a rule defining the harmonic quantizer scale as follows;
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Specification