Image Encoding Device Using Selective Vector Quantization

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Solution Overview

Problem

Existing image encoding and decoding devices suffer from image quality deterioration, especially in graphic-type images, due to nonlinear quantization of high-frequency components and dependence on previous pixel values, leading to increased costs and complexity from block-based encoding methods.

Innovation Solution

An image encoding and decoding device that uses difference vector quantization and absolute value vector quantization selectively, based on comparison ranges, to encode and decode images without dividing them into small blocks, allowing edge parts to be encoded independently of previous pixel values, thereby reducing image quality deterioration.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If an image is divided into small blocks and encoded using blocking method, then encoding efficiency is improved, but device complexity increases due to requirement of block line memory

Engineering Contradiction:

Improveencoding efficiencyVSAvoiddevice complexity

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The patent extracts the problematic block-based encoding structure and replaces it with a line-by-line encoding approach. By removing the block division mechanism and associated block line memory, the system achieves similar encoding efficiency without the complexity overhead of block management structures.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent segments the encoding process into line-level operations rather than block-level operations. By processing images line by line with selective vector quantization applied to individual lines or small groups of lines, the system maintains encoding efficiency while eliminating the need for large block memory structures.

Inventive Principle:

Principle #1Segmentation

2Productivity

If nonlinear quantization is applied to high frequency components in small blocks, then encoding compression is improved, but image quality deteriorates due to quantized error dispersion

Engineering Contradiction:

Improveencoding compressionVSAvoidimage quality

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The patent applies different quantization strategies to different regions within an image line. Edge portions detected in the line are encoded using methods that preserve high-frequency details, while non-edge portions use standard compression. This local differentiation maintains image quality in critical areas while achieving overall compression.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent dynamically changes quantization parameters based on local image characteristics. By detecting edges and adjusting quantization strength accordingly—applying weaker quantization to edge regions and stronger quantization to non-edge regions—the system achieves both compression and quality preservation.

Inventive Principle:

Principle #35Parameter changes

3Productivity

If difference vector quantization is used for encoding, then compression efficiency is improved, but image quality deteriorates in edge parts due to dependence on previous pixel values

Engineering Contradiction:

Improvecompression efficiencyVSAvoidimage quality

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The patent dynamically switches between difference vector quantization and absolute value vector quantization based on edge detection results. In edge portions where previous pixel values are unreliable, the system transitions to absolute value quantization that does not depend on previous pixels, thereby maintaining image quality while preserving compression efficiency in non-edge areas.

Inventive Principle:

Principle #15Dynamics

4Speed

If block-based encoding method is used, then encoding speed is improved, but cost increases due to requirement of block line memory

Engineering Contradiction:

Improveencoding speedVSAvoidcost

Core Design Contradiction:

SpeedVSEase of manufacture

Solution Approach 1:

The patent removes the block line memory component from the encoding system by adopting a line-by-line processing approach. This extraction eliminates the hardware cost associated with large block memory while maintaining encoding speed through efficient line-level vector quantization operations.

Inventive Principle:

Principle #2Taking out (Extraction)

Data Source

PatentUS8270747B2Image encoding device, image decoding device, and integrated circuit

Publication Date: 2012.09.18 SEIKO EPSON CORP

AI summary

An image encoding device that receives a plurality of component values of a color input signal inputted to an object pixel, vector quantizes, and encodes each of the plurality of component values includes: a difference vector quantization unit that vector quantizes and encodes each difference value obtained by subtracting prediction component values based on a previous object pixel from the component values of the object pixel respectively; an absolute value vector quantization unit that vector quantizes and encodes each different value of the object pixel; a determination unit that compares each difference value with respective comparison ranges to determine a code selection; and a code selector that selects one of an output from the difference vector quantization unit and an output from the absolute value vector quantization unit based on an output from the determination unit.