# US 11,445,196 B2 · Method for determining color difference component quantization parameter and device using the method

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- Number: US 11,445,196 B2
- Document ID: US11445196B2
- Status: Granted
- Kind: B2
- Application number: 17/321,715
- Filed: 2021-05-17
- Published: 2021-09-02
- Granted: 2022-09-13
- Earliest claimed: 2011-03-03
- Assignees: Dolby Laboratories Licensing Corporation
- Applicants: Dolby Laboratories Licensing Corporation
- Inventors: Sung Chang Lim; Hui Yong Kim; Se Yoon Jeong; Jong Ho Kim; Ha Hyun Lee; Jin Ho Lee; Jin Soo Choi; Jin Woong Kim
- Web page: https://patentgrep.com/patent/US11445196B2

## CPC

- H04N 19/124: Quantisation
- H04N 19/105: Selection of the reference unit for prediction within a chosen coding or prediction mode, e.g. adaptive choice of position and number of pixels used for prediction
- H04N 19/117: Filters, e.g. for pre-processing or post-processing (sub-band filter banks H04N19/635)
- H04N 19/122: Selection of transform size, e.g. 8x8 or 2x4x8 DCT; Selection of sub-band transforms of varying structure or type
- H04N 19/13: Adaptive entropy coding, e.g. adaptive variable length coding [AVLC] or context adaptive binary arithmetic coding [CABAC]
- H04N 19/15: by monitoring actual compressed data size at the memory before deciding storage at the transmission buffer
- H04N 19/157: Assigned coding mode, i.e. the coding mode being predefined or preselected to be further used for selection of another element or parameter
- H04N 19/159: Prediction type, e.g. intra-frame, inter-frame or bidirectional frame prediction
- H04N 19/186: the unit being a colour or a chrominance component
- H04N 19/43: Hardware specially adapted for motion estimation or compensation
- H04N 19/46: Embedding additional information in the video signal during the compression process (H04N19/517, H04N19/68, H04N19/70 take precedence)
- H04N 19/463: by compressing encoding parameters before transmission
- H04N 19/61: in combination with predictive coding
- H04N 19/174: the region being a slice, e.g. a line of blocks or a group of blocks
- H04N 19/176: the region being a block, e.g. a macroblock
- H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION

## Abstract

Disclosed are a method for determining a color difference component quantization parameter and a device using the method. Method for decoding an image can comprise the steps of: decoding a color difference component quantization parameter offset on the basis of size information of a transform unit; and calculating a color difference component quantization parameter index on the basis of the decoded color difference component quantization parameter offset. Therefore, the present invention enables effective quantization by applying different color difference component quantization parameters according to the size of the transform unit when executing the quantization.

## Claims

### Claim 1

A video decoding apparatus comprising:
an inverse-quantizer configured to determine a size of a quantization group, the quantization group being a group of a plurality of transform blocks to which a same chrominance component quantization parameter is applied, configured to calculate the chrominance component quantization parameter to be applied to the determined quantization group,
configured to inverse-quantize transform coefficients of a transform block included in the determined quantization group by using the calculated chrominance component quantization parameter, and
an inverse-transformer configured to generate a residual block by inverse-transforming the inverse-quantized transform coefficients,
wherein the inverse-quantizer comprises:
a chrominance component quantization parameter index calculator configured to calculate a chrominance component quantization parameter index by using a first chrominance component quantization parameter offset of a picture level, a second chrominance component quantization parameter offset of a slice level and a clipping operation, wherein the first chrominance component quantization parameter offset is extracted from a picture parameter set of a bitstream, and the second chrominance component quantization parameter offset is extracted from a slice header of the bitstream; and
a chrominance component quantization parameter calculator configured to calculate the chrominance component quantization parameter based on a pre-defined mapping table and the chrominance component quantization parameter index.

### Claim 2

A video encoding apparatus comprising:
a transformer configured to generate transform coefficients by transforming coefficients of a transform block;
a quantizer configured to determine a size of a quantization group, the quantization group being a group of a plurality of transform blocks to which a same chrominance component quantization parameter is applied, configured to determine the chrominance component quantization parameter to be applied to the determined quantization group, and configured to quantize the transform coefficients of the transform block included in the determined quantization group by using the determined chrominance component quantization parameter; and
an encoder configured to encode the chrominance component quantization parameter, wherein the encoder comprises:
a chrominance component quantization parameter index calculator configured to calculate a chrominance component quantization parameter index based on a pre-defined mapping table and the chrominance component quantization parameter; and
a chrominance component quantization parameter index encoder configured to encode the chrominance component quantization parameter index by using a first chrominance component quantization parameter offset of a picture level, a second chrominance component quantization parameter offset of a slice level and a clipping operation, wherein the first chrominance component quantization parameter offset is included in a picture parameter set of a bitstream, and the second chrominance component quantization parameter offset is included in a slice header of the bitstream.

### Claim 3

A video encoding apparatus comprising:
a transformer configured to generate transform coefficients by transforming coefficients of a transform block;
a quantizer configured to determine a size of a quantization group, the quantization group being a group of a plurality of transform blocks to which a same chrominance component quantization parameter is applied, configured to determine the chrominance component quantization parameter to be applied to the determined quantization group, and configured to quantize the transform coefficients of the transform block included in the determined quantization group by using the determined chrominance component quantization parameter; and
an encoder configured to encode the chrominance component quantization parameter,
wherein a chrominance component quantization parameter index is calculated by using a first chrominance component quantization parameter offset of a picture level, a second chrominance component quantization parameter offset of a slice level and a clipping operation, wherein the first chrominance component quantization parameter offset is included in a picture parameter set of a bitstream, and the second chrominance component quantization parameter offset is included in a slice header of the bitstream; and
wherein the chrominance component quantization parameter is calculated based on a pre-defined mapping table and the chrominance component quantization parameter index.

### Claim 4

A non-transitory computer-readable recording medium storing a bitstream which is received and decoded by a video decoding apparatus and used to reconstruct a video,
wherein the bitstream comprises a first chrominance component quantization parameter offset of a picture level and a second chrominance component quantization parameter offset of a slice level, wherein the first chrominance component quantization parameter offset is extracted from a picture parameter set of the bitstream, and the second chrominance component quantization parameter offset is extracted from a slice header of the bitstream,
wherein the first chrominance component quantization parameter offset and the second chrominance component quantization parameter offset are used with a clipping operation to calculate a chrominance component quantization parameter index,
wherein the chrominance component quantization parameter index is used with a pre-defined mapping table to calculate a chrominance component quantization parameter,
wherein the chrominance component quantization parameter is applied to a quantization group and used to inverse-quantize transform coefficients of a transform block included in the quantization group,
wherein the inverse-quantized transform coefficients are inverse-transformed to generate a residual block, and
wherein the quantization group is a group of a plurality of transform blocks to which the same chrominance component quantization parameter is applied, a size of the quantization group being determined by the video decoding apparatus.