Full Reflectance Spectrum Acquisition via Combined Calibration
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Solution Overview
Problem
Obtaining a full reflectance spectrum of a surface is challenging when the spectral characteristics of the light source and camera response characteristics are unknown, as existing methods require direct measurement, which is sensitive to external factors and lacks standardization.
Innovation Solution
A method and apparatus that calculate a combined light source spectrum characteristic and camera response characteristic value using a reference object with a known full reflectance spectrum, allowing for the derivation of the full reflectance spectrum of a surface by photographing objects in a predetermined lighting environment, even when the spectral characteristics of the light source and camera are unknown.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If direct measurement methods are used to obtain camera response characteristics, then measurement can be performed, but the measurement is sensitive to external light sources and lacks accuracy
Solution Approach 1:
The patent applies preliminary action by pre-calculating the combined characteristic values of the light source and camera using reference objects with known reflectance spectra before actual measurement. This pre-computation stores the system's response characteristics, eliminating the need for sensitive direct measurements during operation and making the system immune to external light interference.
Solution Approach 2:
The patent introduces reference objects with known full reflectance spectra as intermediaries. These reference objects serve as mediators between the light source-camera system and the unknown characteristics, allowing indirect determination of system characteristics through comparison rather than direct sensitive measurement.
2Measurement precision
If multiple narrow band light sources or color filters are used to measure camera response, then measurement can be performed, but the process becomes complex and requires interpolation
Solution Approach 1:
The patent merges the light source spectrum characteristic and camera response characteristic into a single combined characteristic value. This combination simplifies the measurement process by treating two separate complex characteristics as one unified parameter, eliminating the need for multiple light sources, filters, and interpolation operations.
Solution Approach 2:
The patent changes the parameter representation from separate spectrum and response characteristics to a combined characteristic value. This parameter transformation simplifies the mathematical model and measurement process, converting a complex multi-parameter problem into a simpler single-parameter determination.
3Measurement precision
If reflection spectra from various known objects are used, then measurement can be performed, but accuracy cannot be guaranteed when known spectra are insufficient
Solution Approach 1:
The patent creates a universal measurement method that works for any object regardless of whether its reflectance spectrum is known or unknown. The combined characteristic value approach provides a universal solution that adapts to different objects and lighting conditions, making the system versatile and broadly applicable.
Data Source
AI summary
Disclosed are a method for obtaining a full reflectance spectrum of a surface and an apparatus therefor. The method for obtaining a full reflectance spectrum of a surface, comprises the steps of: (a) calculating a combination value of spectral characteristics of a light source and response characteristics of a camera for an image of a reference object, the full reflectance spectrum of a surface of which is known, by utilizing the known full reflectance spectrum of a surface; (b) obtaining an image by photographing an object irradiated with light according to a predetermined lighting environment; and (c) obtaining a full reflectance spectrum of a surface for the object by utilizing the combination value of the spectral characteristics of the light source and the response characteristics of the camera for the image.