Image encoding apparatus and quantization control method
AssigneeNEC Corporation
InventorJun Awano
Life of this patent
Estimating the term…
Abstract
An image encoding apparatus includes a quantization control section that supplies a rounded Q-scale to a quantization section for quantizing each macroblock according to the rounded Q-scale. A Q-scale is generated for each macroblock based on the amount of generated codes produced by encoding. The Q-scale is rounded within a set range by a rounding control section. The rounded Q-scale is smaller in amount than the Q-scale. Since the same Q-scale values will continue in succession, these can be omitted from a stream, allowing the reduced amount of quantization information and the increased amount of information allocated to images.
Claims15
An image encoding apparatus for encoding an image divided into a plurality of blocks, comprising:
- a quantizer for quantizing data of each block according to a DCT coefficient for said each block;
- a quantization information generator for generating first quantization information for each block based on at least an amount of codes generated by encoding;
- a rounding controller for rounding the first quantization information within a set range to generate second quantization information that is smaller in amount than the first quantization information;
- and
- a selector for selecting the quantization information of an immediately preceding block as the second quantization information when a difference between the quantization information of the immediately preceding block and the first quantization information of the block currently being processed falls within a set range, and selecting the first quantization information as the second quantization information when the difference falls out of the set range.
A quantization control method in an image encoding apparatus wherein an image divided into a plurality of blocks is encoded for each block, comprising:
- a) generating first quantization information for each block based on at least an amount of codes generated by encoding;
- b) generating second quantization information that is smaller in amount than the first quantization information by rounding the first quantization information within a set range;
- c) storing quantization information of an immediately preceding block;
- d) generating a difference between the quantization information of the immediately preceding block and the first quantization information of the block currently being processed;
- and
- e) selecting the quantization information of the immediately preceding block as the second quantization information when the difference falls within the set range.
A program stored on a computer readable storage medium to perform encoding of an image divided into a plurality of blocks, comprising:
- a) generating first quantization information for each block based on at least an amount of codes generated by encoding;
- b) generating second quantization information that is smaller in amount than the first quantization information by rounding the first quantization information within a set range;
- c) storing quantization information of an immediately preceding block;
- d) generating a difference between the quantization information of the immediately preceding block and the first quantization information of the block currently being processed;
- and
- e) selecting the quantization information of the immediately preceding block as the second quantization information when the difference falls within the set range.
Dependencies are inferred from the claim text.