Depth Map Coding Using Sorted DLT and Difference Values
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Solution Overview
Problem
Existing 3D-HEVC methods for coding depth information in three-dimensional video coding are inefficient due to direct writing of DLT values into bitstreams without removing redundancy, leading to excessive bit costs, especially with the RCBM method requiring additional bits to identify depth values within a DLT range.
Innovation Solution
The method arranges all elements in a DLT in ascending order and codes the first element's value and difference values between other elements, with optional entropy coding based on a threshold, to reduce redundancy and bit costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If direct coding method is used to write DLT information into bitstream, then the coding process is simple, but the bit cost is excessive
Solution Approach 1:
The patent extracts only the essential DLT information (minimum value, maximum value, and bit map flags) from the complete DLT data and writes only these extracted elements into the bitstream. This selective extraction reduces bit cost while maintaining the ability to reconstruct the full DLT at the decoder side.
Solution Approach 2:
The patent transforms the DLT representation from storing all depth values to storing statistical parameters (minimum and maximum values) combined with a compact bit map. This parameter transformation reduces the quantity of data that needs to be coded into the bitstream.
2Quantity of substance
If RCBM method is used to code DLT information, then the bit cost is reduced, but additional bits are required to identify depth values
Solution Approach 1:
The patent performs preliminary sorting of DLT elements in ascending order before coding. This preliminary action ensures that the bit map can be efficiently constructed and coded, as the sorted order allows for compact representation of depth value presence/absence without requiring additional identification bits.
Solution Approach 2:
The patent uses a bit map as a compact copy or representation of the DLT depth values, where each bit indicates the presence or absence of a depth value in the sorted sequence. This bit map copying approach reduces bit cost compared to storing actual depth values, while the sorting ensures efficient encoding.
Data Source
AI summary
Disclosed are methods and devices for coding and decoding depth information, which relate to a Three-Dimensional Video (3DV) coding technology. The coding method includes: arranging all elements in a DLT in an ascending order of values, wherein the DLT is a data structure representing depth numerical values by index numbers; coding a value of a first element in the DLT, and writing the bits of the value into a bitstream; and coding a difference value between a value of each of the other elements except the first element in the DLT and a value of an element with an index number smaller than an index number of the each of other elements in the DLT respectively, and writing the value of the difference value into the bitstream. The method for decoding depth information and related coding and decoding devices are also provided. By the technical solutions of the disclosure, efficiency of coding and decoding depth information is improved, and resource occupation during depth information coding is reduced.