Using quantization bias that accounts for relations between transform bins and quantization bins
First Claim
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1. A method comprising:
- receiving plural input values;
producing one or more transform coefficient values by performing a frequency transform on the plural input values; and
quantizing the one or more transform coefficient values, wherein the quantizing includes setting a quantization level for a first transform coefficient value of the one or more transform coefficient values, and wherein the setting uses quantization bias that accounts for relations between quantization bins and transform bins.
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Abstract
Techniques and tools are described for using quantization bias that accounts for relations between transform bins and quantization bins. The techniques and tools can be used to compensate for mismatch between transform bin boundaries and quantization bin boundaries during quantization. For example, in some embodiments, when a video encoder quantizes the DC coefficients of DC-only blocks, the encoder compensates for mismatches between transform bin boundaries and quantization bin boundaries. In some implementations, the mismatch compensation uses an offset table that accounts for the mismatches. In other embodiments, the encoder uses adjustable thresholds to control quantization bias.
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Citations
20 Claims
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1. A method comprising:
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receiving plural input values; producing one or more transform coefficient values by performing a frequency transform on the plural input values; and quantizing the one or more transform coefficient values, wherein the quantizing includes setting a quantization level for a first transform coefficient value of the one or more transform coefficient values, and wherein the setting uses quantization bias that accounts for relations between quantization bins and transform bins. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. An encoder comprising:
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a frequency transformer adapted to perform frequency transforms on plural input values, thereby producing plural transform coefficient values; and a quantizer adapted to quantize the plural transform coefficient values by performing operations that include setting a first quantization level for a first transform coefficient value of the plural transform coefficient values, wherein the setting the first quantization level uses quantization bias that accounts for relations between quantization bins and transform bins. - View Dependent Claims (16, 17, 18, 19)
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20. A video encoder comprising:
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means for producing transform coefficient values by performing frequency transforms on input values for blocks of video images; and means for quantizing the transform coefficient values, wherein the quantizing includes setting a quantization level for a DC transform coefficient value of the transform coefficient values, the DC transform coefficient value being for a DC-only block among the blocks, and wherein the setting accounts for mismatch between quantization bin boundaries and transform bin boundaries.
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Specification