System and method for performing optimized quantization via quantization re-scaling
AssigneeMobilygen Corporation
InventorJiangtao Wen
Life of this patent
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Abstract
A method, system, and program product for quantizing discrete cosine transform coefficients, e.g., for MPEG compression, with minimal bit rate overhead and without using a quantization matrix. This is done by scaling a uniform quantization parameter for the entire discrete cosine transform block, defining a variety of thresholds for the quantization of discrete cosine transform coefficients below which the corresponding coefficient will be quantized to zero, and setting different normative reconstructed values for coefficients that have not been quantized to zero as the decoder will still use the original, unmodified reconstructed values as long as the corresponding coefficient is not zero.
Claims12
A method of quantizing discrete cosine transform coefficients, comprising:
- defining a plurality of thresholds for the quantization of a plurality of transform coefficients;
- quantizing coefficients that correspond to transforms that occur below the thresholds to zero;
- and
- establishing alternative reconstructed values for coefficients other than those quantized to zero;
- selecting a uniform quantization step size for the entire block of coefficients so that the alternative reconstructed values are either multiples of the uniform quantization step size determined, and close to multiples of the uniform quantization step size;
- and
- composing a standard compliant bitstream which can be decoded by any standard decoder following standard inverse quantization procedure and reproduce reconstruction values mandated by the encoder.
Dependencies are inferred from the claim text.