Depth Image Compression Using Stereo Difference Data
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Solution Overview
Problem
The transmission of high-accuracy depth information alongside color images in VR and AR applications often results in degraded image quality or increased data size due to bandwidth limitations, particularly in large-scale networks or wireless communication.
Innovation Solution
An image processing device that compresses depth image data using redundancy from stereo images and decompresses it at a content processing device, allowing for high-accuracy processing without increasing transmission data size, by utilizing a difference image between measured and generated depth images, and adjusting gradations based on subject distance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If depth information is transmitted together with color image data, then measurement accuracy is improved, but transmission data size increases
Solution Approach 1:
The patent segments depth information transmission into two parts: (1) transmission of color images from multiple viewpoints, and (2) transmission of only the difference image between actual depth and generated depth. This segmentation allows the system to maintain high depth accuracy while significantly reducing the quantity of transmitted data, as the difference image contains far fewer bits than complete depth maps.
Solution Approach 2:
The patent introduces an intermediary process where a depth image is generated from color images using stereo vision algorithms, and then only the difference between this generated depth and actual measured depth is transmitted. This intermediary approach acts as a mediator that reduces transmission data while preserving measurement accuracy through error compensation.
2Productivity
If compression ratio is increased to fit bandwidth, then transmission efficiency is improved, but image quality is degraded
Solution Approach 1:
The patent applies local quality by transmitting full-precision color images while transmitting only compressed difference data for depth information. The color images maintain their original quality, while the depth difference data uses a compact representation that is sufficient for maintaining depth accuracy without requiring full transmission of complete depth maps.
Solution Approach 2:
The patent changes the parameter representation from transmitting complete depth maps to transmitting only the difference values between actual and generated depth images. This parameter transformation significantly reduces the data size while maintaining the essential depth information needed for accurate processing.
3Quantity of substance
If resolution of color image is lowered to accommodate depth data, then transmission bandwidth utilization is improved, but image quality is degraded
Solution Approach 1:
The patent segments the transmission data into color images and depth difference information, allowing each to be optimized independently. Color images are transmitted at full resolution while depth information is transmitted as compact difference data, eliminating the need to lower color image resolution and maintaining both bandwidth efficiency and image quality.
Data Source
AI summary
In a depth image compressing section of an image processing device, a depth image operation section generates a depth image by operation using photographed stereo images. A difference image obtaining section generates a difference image between an actually measured depth image and the computed depth image. In a depth image decompressing section of a content processing device, a depth image operation section generates a depth image by operation using the transmitted stereo images. A difference image adding section restores a depth image by adding the computed depth image to the transmitted difference image.