Light Source Estimation Using Sensitivity Ratio Spatial Distribution
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Solution Overview
Problem
Conventional light source estimating apparatuses face challenges in accurately distinguishing between the color of an object and the influence of the light source, leading to degraded accuracy in light source estimation, especially when the object's color deviates significantly.
Innovation Solution
The apparatus calculates the sensitivity ratio spatial distribution using specific color pixels with close spectral sensitivity and different sensor responses, and compares this distribution with reference data to estimate the light source, reducing the object's color influence by using a similarity determination method based on the sum of square differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional light source estimation methods using sensitivity ratios between color pixels are used, then light source estimation can be performed, but accuracy degrades when object color deviates significantly due to inability to distinguish object color from light source influence
Solution Approach 1:
The patent segments the sensitivity ratio calculation into multiple wavelength bands rather than using a single overall sensitivity ratio. By dividing the spectral range into multiple bands and calculating sensitivity ratios for each band separately, the method can identify which bands are affected by object color and which are more indicative of light source characteristics, thereby improving accuracy under varying object colors.
Solution Approach 2:
The patent transitions from a single sensitivity ratio value to a multi-dimensional sensitivity ratio distribution across different wavelength bands. This dimensional expansion allows the system to analyze spectral characteristics more comprehensively and distinguish between object color effects and light source effects by examining patterns across multiple spectral dimensions.
2Loss of information
If sensitivity ratio calculation uses all color pixels, then comprehensive color information is obtained, but object color influence significantly affects light source estimation accuracy
Solution Approach 1:
The patent extracts and isolates the object color influence from the sensitivity ratio calculation by identifying and separating spectral regions where object color has significant impact. By taking out the object color component and analyzing the remaining sensitivity ratio characteristics, the method can estimate light source properties more accurately without contamination from object color variations.
Solution Approach 2:
The patent introduces spectral band selection as an intermediary step between raw pixel data and light source estimation. By using wavelength band segmentation as a mediator, the system can filter out object color influence while preserving light source information, enabling more accurate estimation through the intermediate spectral analysis layer.
Data Source
AI summary
A light source estimating apparatus of embodiments has a sensitivity ratio spatial distribution calculating unit configured to extract a first color pixel and a second color pixel which have close spectral sensitivity and which have different sensor responses from a first picked up image picked up with an image sensor under an arbitrary light source, and calculate a ratio between a signal value of the first color pixel and a signal value of the second color pixel to acquire a first sensitivity ratio spatial distribution, and a similarity determining unit configured to estimate a type of the arbitrary light source based on similarity between a second sensitivity ratio spatial distribution group calculated using a second picked up image picked up with the image sensor under a known light source and the first sensitivity ratio spatial distribution.