Quantization control for variable bit depth

A method for digital encoding, comprising

• processing digital symbols representing a moving image, each symbol S having a bit depth N, to provide intermediate variables X, each having a bit depth N+K, where K is a function of the processing, quantizing each intermediate variable X with a quantizing step size QSN to produce a quantized data word Q, wherein QSN is a function of a quantization parameter QP, which function has been normalized to the most significant bit of the N-bit bit depth,
• processing, including entropy coding, the quantized data words Q to provide an encoded bitstream,
• processing, including entropy decoding, the encoded bitstream, to provide quantized data words Q,
• dequantizing each quantized data word Q with a dequantization step size QSM to produce a dequantized intermediate (M+K)-bit variable X′ that approximates the intermediate (N+K)-bit variable X, wherein QSM is the same function of the quantization parameter QP as is QSN but has been normalized to the most significant bit of an M-bit bit depth, and
• processing the intermediate variables X′ to produce digital symbols, each symbol S′ having a bit depth M, representing an approximation of said moving image.

A method for digital encoding and decoding, comprising

• processing digital symbols representing a moving image, each symbol S having a bit depth Nc, where Nc is a function of the color component c, where c represents one of the color components RGB or YUV or equivalent, to provide intermediate variables Xc, each having a bit depth Nc+K, where K is a function of the processing,
• quantizing each intermediate variable Xc with a quantizing step size QSNC to produce a quantized data word Qc, wherein QSNC is a function of a quantization parameter QP, which function has been normalized to the most significant bit of the Nc-bit bit depth,
• processing, including entropy coding, the quantized data words Qc to provide an encoded bitstream,
• processing, including entropy decoding, the encoded bitstream, to provide quantized data words Qc,
• dequantizing each quantized data word Qc with a dequantization step size QSMc to produce a dequantized intermediate (Mc+K)-bit variable Xc′ that approximates the intermediate (Nc+K)-bit variable Xc, where Mc is also a function of the color component c, wherein QSMC is the same function of the quantization parameter QP as is QSNc but has been normalized to the most significant bit of an Mc-bit bit depth, and
• processing the intermediate variables Xc′ to produce digital symbols, each symbol S′ having a bit depth Mc, representing an approximation of said moving image.

A method for decoding a bitstream wherein the bitstream was generated by processing digital symbols representing a moving image, each symbol S having a bit depth N, to provide intermediate variables X, each having a bit depth N+K, where K is a function of the processing;

• quantizing each intermediate variable X with a quantizing step size QSN to produce a quantized data word Q, wherein QSN is a function of a quantization parameter QP, which function has been normalized to the most significant bit of the N-bit bit depth;
• and processing, including entropy coding, the quantized data words Q to provide an encoded bitstream, comprising
• processing, including entropy decoding, the encoded bitstream, to provide quantized data words Q,
• dequantizing each quantized data word Q with a dequantization step size QSM to produce a dequantized intermediate (M+K)-bit variable X′ that approximates the intermediate (N+K)-bit variable X, wherein QSM is the same function of the quantization parameter QP as is QSN but has been normalized to the most significant bit of an M-bit bit depth, and
• processing the intermediate variables X′ to produce digital symbols, each symbol S′ having a bit depth M, representing an approximation of said moving image.

Apparatus for digital encoding and decoding, comprising

• means for processing digital symbols representing a moving image, each symbol S having a bit depth N, to provide intermediate variables X, each having a bit depth N+K, where K is a function of the processing,
• means for quantizing each intermediate variable X with a quantizing step size QSN to produce a quantized data word Q, wherein QSN is a function of a quantization parameter QP, which function has been normalized to the most significant bit of the N-bit bit depth,
• means for processing, including entropy coding, the quantized data words Q to provide an encoded bitstream,
• means for processing, including entropy decoding, the encoded bitstream, to provide quantized data words Q,
• means for dequantizing each quantized data word Q with a dequantization step size QSM to produce a dequantized intermediate (M+K)-bit variable X′ that approximates the intermediate (N+K)-bit variable X, wherein QSM is the same function of the quantization parameter QP as is QSN but has been normalized to the most significant bit of an M-bit bit depth, and
• means for processing the intermediate variables X′ to produce digital symbols, each symbol S′ having a bit depth M, representing an approximation of said moving image.

Apparatus for digital encoding, comprising

• means for processing digital symbols representing a moving image, each symbol S having a bit depth N, to provide intermediate variables X, each having a bit depth N+K, where K is a function of the processing,
• means for quantizing each intermediate variable X with a quantizing step size QSN to produce a quantized data word Q, wherein QSN is a function of a quantization parameter QP, which function has been normalized to the most significant bit of the N-bit bit depth,
• means for processing, including entropy coding, the quantized data words Q to provide an encoded bitstream,
• means for processing, including entropy decoding, the encoded bitstream, to provide quantized data words Q,
• means for dequantizing each quantized data word Q with a dequantization step size QSM to produce a dequantized intermediate (M+K)-bit variable X′ that approximates the intermediate (N+K)-bit variable X, wherein QSM is the same function of the quantization parameter QP as is QSN but has been normalized to the most significant bit of an M-bit bit depth, and
• means for processing the intermediate variables X′ to produce digital symbols, each symbol S′ having a bit depth M, representing an approximation of said moving image.

Apparatus for digital encoding and decoding, comprising

• means for processing digital symbols representing a moving image, each symbol S having a bit depth Nc, where Nc is a function of the color component c, where c represents one of the color components RGB or YUV or equivalent, to provide intermediate variables Xc, each having a bit depth Nc+K, where K is a function of the processing,
• means for quantizing each intermediate variable Xc with a quantizing step size QSNC to produce a quantized data word Qc, wherein QSNC is a function of a quantization parameter QP, which function has been normalized to the most significant bit of the Nc-bit bit depth,
• means for processing, including entropy coding, the quantized data words Qc to provide an encoded bitstream,
• means for processing, including entropy decoding, the encoded bitstream, to provide quantized data words Qc,
• means for dequantizing each quantized data word Qc with a dequantization step size QSMC to produce a dequantized intermediate (Mc+K)-bit variable Xc′ that approximates the intermediate (Nc+K)-bit variable Xc, where Mc is also a function of the color component c, wherein QSMC is the same function of the quantization parameter QP as is QSNc but has been normalized to the most significant bit of an Mc-bit bit depth, and
• means for processing the intermediate variables Xc′ to produce digital symbols, each symbol S′ having a bit depth Mc, representing an approximation of said moving image.

Apparatus for decoding a bitstream wherein the bitstream was generated by processing digital symbols representing a moving image, each symbol S having a bit depth N, to provide intermediate variables X, each having a bit depth N+K, where K is a function of the processing;

• quantizing each intermediate variable X with a quantizing step size QSN to produce a quantized data word Q, wherein QSN is a function of a quantization parameter QP, which function has been normalized to the most significant bit of the N-bit bit depth;
• and processing, including entropy coding, the quantized data words Q to provide an encoded bitstream, comprising
• means for processing, including entropy decoding, the encoded bitstream, to provide quantized data words Q,
• means for dequantizing each quantized data word Q with a dequantization step size QSM to produce a dequantized intermediate (M+K)-bit variable X′ that approximates the intermediate (N+K)-bit variable X, wherein QSM is the same function of the quantization parameter QP as is QSN but has been normalized to the most significant bit of an M-bit bit depth, and
• means for processing the intermediate variables X′ to produce digital symbols, each symbol S′ having a bit depth M, representing an approximation of said moving image.