Camera System Internal Reference Illumination for Color Fidelity
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Solution Overview
Problem
Camera systems relying on color image sensors for object inspection and measurement face challenges due to the instability of illumination sources caused by aging and temperature changes, which require frequent white balancing to maintain color fidelity, leading to delayed measurements.
Innovation Solution
Incorporating an internal reference illumination light source that allows for cyclic imaging without the objective arrangement, enabling correction of aging and temperature effects by relating intermediate images taken under this source to images taken with the primary illumination source, thereby reducing the need for repeated white balancing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If frequent white balancing is performed to maintain color fidelity, then color accuracy is improved, but measurement time increases and productivity decreases
Solution Approach 1:
The system performs preliminary characterization of the illumination source spectral properties and stores reference data. During operation, instead of performing full white balancing, the system uses pre-stored correction factors and intermediate images to compensate for spectral changes, thereby maintaining color fidelity without time-consuming repeated white balancing procedures
Solution Approach 2:
The system creates intermediate images under controlled illumination conditions and uses these copies to represent and correct the actual measurement images. By comparing and relating intermediate images to images taken with the primary illumination source, the system can correct aging and temperature effects without requiring repeated white balancing of the actual objects
2Illumination intensity
If multiple illumination LEDs are used to provide full color spectrum, then illumination quality is improved, but individual aging of different color channels occurs causing spectral instability
Solution Approach 1:
The system implements continuous monitoring of the illumination source spectral properties by cyclically capturing intermediate images and comparing them with reference images. This feedback mechanism detects aging and temperature effects on individual LED channels, enabling real-time correction of spectral instability through gain adjustments and color channel balancing
Solution Approach 2:
The camera system integrates multiple functions into a single platform: it performs both object inspection/measurement and illumination source characterization using the same color image sensor. The system uses the color image sensor to capture both measurement images and intermediate images for white balance correction, eliminating the need for separate reference measurement devices
3Device complexity
If white LED is used as illumination source, then device complexity is reduced, but spectral shift to longer wavelengths occurs during operation
Solution Approach 1:
The system continuously monitors the white LED spectral output by capturing intermediate images and comparing them with reference images. When spectral shifts are detected, the system automatically adjusts the color balance and applies correction factors to maintain accurate color representation, thereby compensating for the inherent spectral instability of white LEDs
Solution Approach 2:
The system replaces complex mechanical or optical solutions for maintaining spectral stability with a software-based correction approach. Instead of using multiple stable light sources or complex optical filters, the system uses digital image processing and color channel adjustments to compensate for white LED spectral drift
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
This approach minimizes the dependence on temperature and aging effects, allowing for continuous operation with reduced measurement delays and improved color fidelity by accounting for spectral changes in the illumination sources.
Implementation Method 1
a color image sensor, an objective arrangement in front of the color image sensor for imaging an object from the environment on the color image sensor
Implementation Method 2
at least one taking illumination light source with which the environment can be illuminated by non-monochromatic light
Data Source
AI summary
The invention relates to a camera system for inspecting and/or measuring objects in an environment, comprising a color image sensor, an objective arrangement in front of the color image sensor for imaging an object from the environment on the color image sensor and at least one taking illumination light source with which the environment can be illuminated by non-monochromatic light, in particular without passing through the objective arrangement. In accordance with the invention, an internal reference illumination light source is provided which is arranged such that the color image sensor can be illuminated by it without the light irradiated by it for this purpose passing through the objective arrangement. The invention furthermore relates to a method for inspecting and/or measuring objects using such a camera system.