Perceptual Visual Quality Evaluation Using DC and AC Coefficients
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Solution Overview
Problem
Existing methods for evaluating perceptual visual quality (PVQ) of compressed images are computationally intensive, making them impractical for video monitoring, particularly in H.262 or H.264 I-frames without block transforms or prediction.
Innovation Solution
A method that decodes I-frames within a group of pictures, determines DC and AC coefficients for selected macroblocks, and calculates PVQ without performing block transforms or prediction, using frequency domain analysis and simplified calculations to assess macroblocking and image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If spatial filtering and edge detection algorithms are performed on complete decoded video image streams to evaluate perceptual visual quality, then measurement precision is improved, but use of energy increases and productivity decreases
Solution Approach 1:
The patent segments the video evaluation process by focusing only on I-frames within GOPs and selectively analyzing specific macroblocks rather than processing complete decoded video streams. This segmentation reduces computational load while maintaining representative quality assessment through DC and AC coefficient analysis of selected blocks.
Solution Approach 2:
The patent extracts only the essential frequency domain coefficients (DC and AC coefficients) needed for quality evaluation from the compressed bitstream, avoiding the need to perform complete block transforms and predictions. This extraction approach retrieves sufficient quality information with minimal computational effort.
2Measurement precision
If spatial filtering and edge detection algorithms are performed on complete decoded video image streams to evaluate perceptual visual quality, then measurement precision is improved, but productivity decreases
Solution Approach 1:
The patent segments the video evaluation process by focusing only on I-frames within GOPs and selectively analyzing specific macroblocks rather than processing complete decoded video streams. This segmentation reduces computational load while maintaining representative quality assessment through DC and AC coefficient analysis of selected blocks.
Solution Approach 2:
The patent extracts only the essential frequency domain coefficients (DC and AC coefficients) needed for quality evaluation from the compressed bitstream, avoiding the need to perform complete block transforms and predictions. This extraction approach retrieves sufficient quality information with minimal computational effort.
3Measurement precision
If block transforms and predictions are performed to evaluate perceptual visual quality of compressed video bit streams, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent extracts only the essential frequency domain coefficients (DC and AC coefficients) needed for quality evaluation from the compressed bitstream, avoiding the need to perform complete block transforms and predictions. This extraction approach retrieves sufficient quality information with minimal computational effort.
Solution Approach 2:
The patent uses DC and AC coefficients as proxies or copies that represent the essential quality characteristics of the video content without requiring full reconstruction of the image through block transforms. These coefficient copies provide sufficient information for quality assessment with reduced complexity.
Data Source
AI summary
A method of evaluating perceptual visual quality (PVQ) of compressed video bit streams in the H.262 or H.264 formats without performing block transforms or prediction decodes I-frames within a group of pictures (GOP). DC and AC coefficients are determined for selected macroblocks within a selected one of the I-frames. Based upon the DC and AC coefficients, the PVQ is calculated.