Depth Map Coding Using Intra-Mode Directivity Prediction
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Solution Overview
Problem
Current methods for coding and transmitting depth images are inefficient due to high data size and the need for multiple views in 3D imaging applications, such as free viewpoint TV and 3D TV, which strain network infrastructure and bandwidth.
Innovation Solution
A depth image coding apparatus and method that includes an intra-mode prediction unit, intra-coding unit, inter-coding unit, and coding mode determination unit to predict the directivity of macro blocks using adjacent coded blocks, prioritize coding modes based on rate distortion optimization, and apply deblocking filters to reduce data size and improve transmission efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple views are coded and transmitted for stereoscopic imaging, then 3D depth impression and viewing quality are improved, but data size and network bandwidth requirements increase significantly
Solution Approach 1:
The patent extracts and transmits only the depth information (distance values) separately from the color image data. Instead of transmitting multiple full-resolution color views, the system extracts depth maps that represent distance information, significantly reducing the quantity of data that needs to be transmitted while preserving the essential 3D depth perception capability.
Solution Approach 2:
The patent changes the parameter representation by encoding depth information using a separate depth map with distance values (0-255 scale) rather than transmitting multiple complete color images. This parameter transformation allows the system to represent 3D spatial information more efficiently, reducing data transmission requirements while maintaining depth perception quality.
2Measurement precision
If depth image is coded with high precision to maintain quality, then depth information accuracy is improved, but coding complexity and data size increase
Solution Approach 1:
The patent applies parameter changes by using a simplified depth encoding scheme with 8-bit depth values (0-255 range) to represent distance information. This parameter quantization maintains sufficient depth accuracy for 3D perception while significantly reducing coding complexity compared to transmitting full-resolution color images or using higher precision depth formats.
3Ease of operation
If conventional color image coding methods are applied to depth images, then coding process is simplified, but coding efficiency is reduced due to flat characteristics of depth images
Solution Approach 1:
The patent applies local quality by treating depth image coding differently from color image coding. Specifically, it uses intra-prediction modes adapted for the flat, gradient-like characteristics of depth maps, and applies deblocking filters with parameters optimized for depth data. This localized adaptation of coding strategies improves coding efficiency for depth images while maintaining operational simplicity through dedicated processing paths.
Data Source
AI summary
An apparatus and method for coding and decoding a depth image are provided. The depth image coding apparatus predicts directivity of a current macro block using coded adjacent macro blocks. An intra-prediction mode that intra-codes the current macro block using the predicted directivity is included in intra-candidate coding modes. Priorities of intra-candidate coding modes and inter-candidate coding modes are arranged according to characteristics of a color image and coded. As a result, coding efficiency for a depth image may be increased.