Stereo Image Color Calibration via Smoothed Mapping Functions
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Solution Overview
Problem
Calibration inequalities between stereo views in 3D video capture systems, particularly color calibration issues, lead to errors in stereo matching algorithms and a suboptimal 3D effect, which existing methods struggle to address effectively, especially in real-time applications like 3D TV.
Innovation Solution
A method that generates a mapping function to align the color dynamic range of one stereo image with another, smoothing the mapping function to remove discontinuities and applying it to moderate the color of the images, using cumulative histograms and weighted modification to prevent artefacts, and incorporating a temporal filter to reduce flicker.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a mapping function is generated to calibrate color between stereo views, then color calibration accuracy is improved, but discontinuities in the mapping function cause visual artefacts
Solution Approach 1:
The patent applies local quality by detecting discontinuities at specific locations in the mapping function and applying localized smoothing only in those regions. The smoothing operation is weighted and adaptive, concentrating computational effort where discontinuities exist rather than uniformly processing the entire mapping function, thus reducing artefacts while preserving calibration accuracy in well-behaved regions.
Solution Approach 2:
The patent introduces an intermediary smoothing operation between the raw mapping function generation and its application to images. This intermediary process detects discontinuities and applies weighted smoothing to create a modified mapping function that serves as a mediator, balancing the competing demands of calibration accuracy and artefact reduction.
2Reliability
If color calibration is performed on stereo images, then 3D effect quality is improved, but processing time increases
Solution Approach 1:
The patent segments the color calibration process into distinct stages: mapping function generation, discontinuity detection, selective smoothing, and final application. This segmentation allows each stage to be optimized independently and enables early termination or approximation in subsequent stages if time constraints arise, maintaining quality while reducing overall processing time.
Solution Approach 2:
The patent implements partial action by applying smoothing only to regions where discontinuities are detected, rather than processing the entire mapping function uniformly. This selective approach reduces computational load while maintaining calibration quality in critical regions, achieving a balance between processing time and 3D effect quality.
3Measurement precision
If cumulative histograms are used for color equalisation, then colour calibration is achieved, but discontinuities and flat regions are introduced in the mapping function
Solution Approach 1:
The patent converts the harmful effect of discontinuities and flat regions introduced by cumulative histogram equalisation into a detectable pattern. By specifically detecting these discontinuities and applying targeted smoothing, the patent transforms the originally harmful artifact into a controlled feature that can be systematically corrected, thereby maintaining the benefits of histogram-based equalisation while eliminating its drawbacks.
Data Source
AI summary
The invention provides a method of calibration of stereo images, the method comprising: receiving first and second images representing the two images from a stereo image capture device; generating a first mapping function to map the colour range of the first image to that of the second image; moderating the first mapping function to generate a smoothed mapping function; and applying the mapping function to moderate the colour of the first image.