Light-measuring system look-up table for color coordinate accuracy
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Solution Overview
Problem
Existing light-measuring systems face challenges in accurately measuring light spectra due to uneven responsivity of light-sensing elements, leading to errors in color coordinates, especially for lights with small waviness width, and struggle to normalize variations in light spectra, resulting in significant measurement errors.
Innovation Solution
A light-measuring system and method that constructs a look-up table based on a light spectrum model, using spectrum parameters like central wavelength and half-power full waviness width to accurately determine color coordinates and luminance, correcting actual stimulus values with standard color-matching functions, thereby reducing measurement errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If standard color-matching functions XS(λ), YS(λ) and ZS(λ) are used for measurement, then color coordinates can be obtained, but manufacturing precision deteriorates because it is difficult to manufacture optical filters that meet the three standard color-matching functions
Solution Approach 1:
The patent changes the measurement approach from direct spectral measurement using precise optical filters to measuring three specific color coordinates (Xs, Ys, Zs) that characterize the light source's spectral properties. By measuring these parameter values and using them to query a pre-built look-up table, the system achieves accurate color coordinate determination without requiring difficult-to-manufacture optical filters that exactly match standard color-matching functions.
2Ease of operation
If actual color-matching functions with uneven responsivity are used, then measurement can be performed, but measurement precision deteriorates due to unavoidable errors in stimulus values
Solution Approach 1:
The patent creates a look-up table that stores the relationship between spectrum parameters and color coordinates, obtained through offline calculations using standard color-matching functions. During actual measurement, instead of performing complex spectral integration with uneven responsivity functions, the system copies the pre-calculated relationship from the look-up table based on measured stimulus values, achieving high precision without requiring perfect optical filters.
Solution Approach 2:
The patent performs preliminary calculations offline to build the look-up table, which contains the mapping between stimulus values and accurate color coordinates. This preliminary action eliminates the need for complex real-time calculations during measurement, allowing the system to achieve high precision by simply querying the pre-computed table with measured values.
3Stability of the object's composition
If normalization is performed using regulation constants, then variations can be reduced, but measurement precision deteriorates for lights with small waviness width such as monochromatic light
Solution Approach 1:
The patent applies different measurement and correction strategies based on the local characteristics of the light source. By measuring three specific color coordinates (Xs, Ys, Zs) that capture the local spectral properties, and using these to query the look-up table, the system adapts to different light types including monochromatic lights with small waviness width, achieving high precision without uniform normalization that introduces errors.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system achieves high accuracy in measuring light spectra and color coordinates by constructing a look-up table that accounts for spectral features, allowing for precise determination of light spectrum parameters and luminance, effectively minimizing measurement errors across various light types, including LEDs and monochromatic lights.
Implementation Method 1
a light-sensing element for sensing the at least one of the to-be-measured lights and for producing three stimulus values respectively corresponding to the three color coordinates
Data Source
AI summary
The invention discloses a method of constructing light-measuring look-up table, a light-measuring method, and a light-measuring system. The method of constructing light-measuring look-up table is to construct a look-up table by according to spectrum parameters relative to a light spectrum model, three actual color-matching functions relative to the light-measuring system and three standard color-matching functions, calculating both a look-up color coordinate and a reference color coordinate corresponding to each of the spectrum parameters. The light-measuring method includes: first, measuring a to-be-measured light by the light-measuring system to obtain actual stimulus values and calculating an actual color coordinate; then, comparing the actual color coordinate with the look-up color coordinates to determine both a to-be-measured light spectrum parameter and an estimated color coordinate relative to the to-be-measured light; furthermore, according to the to-be-measured light spectrum parameter, one of the standard color-matching functions and one of the actual stimulus values, calculating an estimated luminance.