DSC Coder Distortion Calculation for Visually Lossless Compression

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Solution Overview

Problem

Existing video compression technologies for display links, such as DSC, face challenges in achieving visually lossless compression while being easy and inexpensive to implement, especially for high-resolution displays that require large bandwidth, which current methods often fail to meet due to complexity and cost in conventional hardware.

Innovation Solution

A DSC coder is developed using a block or slice-based approach with multiple coding modes like transform, prediction, and differential pulse-code modulation, allowing for fixed-rate and visually lossless compression by evaluating rate distortion performance in various color spaces and applying appropriate color transformations to residue blocks.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If image compression is applied to pixel data to reduce bandwidth requirements, then bandwidth efficiency is improved, but visual quality is degraded or implementation complexity increases

Engineering Contradiction:
Improvebandwidth requirementsVSAvoidvisual quality
Core Design Contradiction:
Loss of energyVSLoss of information

Solution Approach 1:

The patent applies color space transformation as a parameter change technique. It converts pixel data from the original color space to a transformed color space (such as converting from RGB to YCoCg or other luminance-chrominance color spaces) before compression. This transformation reparameterizes the data to separate luminance and chrominance components, allowing for more efficient compression that preserves visual quality while reducing bandwidth requirements.

Inventive Principle:
Principle #35Parameter changes

2Loss of energy

If conventional image compression schemes are used, then bandwidth requirements are reduced, but implementation becomes difficult and expensive in conventional display devices

Engineering Contradiction:
Improvebandwidth requirementsVSAvoidimplementation complexity
Core Design Contradiction:
Loss of energyVSDevice complexity

Solution Approach 1:

The patent segments the compression process into distinct functional stages: color space transformation, compression, and inverse transformation. By dividing the complex compression task into manageable segments, each can be implemented efficiently with conventional hardware. The segmentation allows for modular implementation that reduces overall system complexity while maintaining compression effectiveness.

Inventive Principle:
Principle #1Segmentation

3Productivity

If multiple coding modes are evaluated for optimal compression, then compression efficiency is improved, but calculation time and complexity increase

Engineering Contradiction:
Improvecompression efficiencyVSAvoidcalculation time
Core Design Contradiction:
ProductivityVSLoss of time

Solution Approach 1:

The patent applies partial action by evaluating only the most promising coding modes rather than exhaustively testing all possible modes. It uses heuristics and preliminary analysis to identify and test a subset of likely optimal modes, achieving good compression efficiency without the full computational burden of exhaustive search. This partial evaluation approach balances compression performance with calculation time constraints.

Inventive Principle:
Principle #16Partial or excessive action

Data Source

PatentEP3403408B1Calculating distortion in display stream compression (DSC)
Publication Date: 2023.05.03 QUALCOMM INC
  • EP3403408B1 patent drawingFigure 1A
  • EP3403408B1 patent drawingFigure 1B
  • EP3403408B1 patent drawingFigure 2

AI summary

Systems and methods are disclosed for calculating a distortion value of a frame or block, in a number of color spaces, and determining an optimal coding mode based on the calculated distortion values. One embodiment includes a system having a video source that includes a video camera or a video archive that contains previously stored video content, and a processor configured to encode the stored video content.