# US 2017/0289546 A1 · Quantization Control for Variable Bit Depth

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- Number: US 2017/0289546 A1
- Document ID: US20170289546A1
- Status: Published application
- Kind: A1
- Application number: 15/625,192
- Filed: 2017-06-16
- Published: 2017-10-05
- Earliest claimed: 2004-05-19
- Assignees: Dolby Laboratories Licensing Corporation
- Applicants: Dolby Laboratories Licensing Corporation
- Inventors: Walter C. Gish; Christopher J. Vogt
- Web page: https://patentgrep.com/patent/US20170289546A1

## CPC

- H04N 19/124: Quantisation
- H04N 19/126: Details of normalisation or weighting functions, e.g. normalisation matrices or variable uniform quantisers
- H04N 19/184: the unit being bits, e.g. of the compressed video stream
- H04N 19/61: in combination with predictive coding
- H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION

## Abstract

The quantization parameter QP is well-known in digital video compression as an indication of picture quality. Digital symbols representing a moving image are quantized with a quantizing step that is a function QSN of the quantization parameter QP, which function QSN has been normalized to the most significant bit of the bit depth of the digital symbols. As a result, the effect of a given QP is essentially independent of bit depth a particular QP value has a standard effect on image quality, regardless of bit depth. The invention is useful, for example, in encoding and decoding at different bit depths, to generate compatible, bitstreams having different bit depths, and to allow different bit depths for different components of a video signal by compressing each with the same fidelity (i.e., the same QP).

## Claims

### Claim 1

A data storage apparatus comprising:
a non-transitory digital memory; and
an encoded bitstream of an intra-predicted image stored on the non-transitory digital memory, the encoded bitstream having a bit depth greater than 8 and including data identifying:
a signed quantization parameter QP that determines a step size for the bit depth, wherein the step size equals 2(the bit depth-8)*QS8; and
quantized digital symbols;
wherein QS8 equals 2QP/6-L.

### Claim 2 (depends on 1)

The data storage apparatus of claim 1 wherein the quantized digital symbols are quantized by the step size.

### Claim 3 (depends on 1)

The data storage apparatus of claim 1 wherein the bit depth equals 12.

### Claim 4 (depends on 1)

The data storage apparatus of claim 1 wherein the bit depth equals 14.

### Claim 5 (depends on 1)

The data storage apparatus of claim 1 wherein the bit depth equals 16.

### Claim 6 (depends on 1)

The data storage apparatus of claim 1 wherein the encoded bitstream is encoded by arithmetic coding.

### Claim 7 (depends on 1)

The data storage apparatus of claim 1 wherein the encoded bitstream is encoded by variable length coding.