Imaging Sensor Calibration Using LED Spectral Sources
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Solution Overview
Problem
Consumer cameras lack the necessary calibration for accurate scientific measurements, particularly in capturing spectral and amplitude data, which is crucial for applications like monitoring light pollution affecting sea turtles, due to their non-linear response across the spectrum and the high cost of existing calibration standards.
Innovation Solution
A cost-effective camera calibration system using monochromatic lasers and the sun as calibration sources, eliminating the need for expensive reflective surfaces and providing a portable, inexpensive method to generate calibration data for consumer cameras, enabling accurate spectral and amplitude calibration of imaging sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If expensive calibrated reflective surfaces and standard luminaires are used for calibration, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent extracts the essential calibration function from complex commercial calibration systems. Instead of using expensive calibrated reflective surfaces and standard luminaires, the invention uses a simple LED light source combined with a spectrometer to capture spectral data, eliminating unnecessary complexity while maintaining calibration accuracy
Solution Approach 2:
The patent creates a simplified copy of the calibration process using readily available components. The system captures spectral power distribution data using an LED and spectrometer, then uses this captured spectral information to generate calibration coefficients, effectively copying the essential measurement function without requiring expensive reference standards
2Device complexity
If consumer cameras are used for scientific measurements, then device complexity and cost are reduced, but measurement precision deteriorates due to non-linear spectral response
Solution Approach 1:
The patent implements a feedback-based calibration process. The system captures spectral data using the consumer camera, compares it against known spectral power distribution data from the LED source, and iteratively adjusts calibration coefficients until accurate spectral reconstruction is achieved. This feedback loop enables consumer cameras to achieve scientific measurement accuracy
Solution Approach 2:
The patent transforms the camera's raw RGB responses into accurate spectral measurements by applying calibration coefficients that correct for non-linear spectral response. The system changes the parameter space from simple RGB values to calibrated spectral power distribution, enabling scientific measurements from consumer devices
3Measurement precision
If accurate spectral calibration is implemented, then measurement precision is improved, but ease of operation deteriorates due to complex calibration procedures
Solution Approach 1:
The patent implements a self-service calibration approach where the system automatically captures spectral data, processes it through the calibration algorithm, and generates calibration coefficients without requiring manual intervention or specialized operator skills. The entire calibration process is automated, making it easy to operate while maintaining high accuracy
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
Enables the production of scientifically calibrated images from consumer cameras, allowing for precise comparison and analysis of data across multiple devices, facilitating citizen science initiatives and improving the accuracy of light pollution measurements.
Implementation Method 1
a light source comprising a light emitting diode (LED)
Implementation Method 2
The LED light source is imaged through a diffraction grating or refracting prism which spatially disperses the spectrum
Implementation Method 3
The LED light source is imaged through a diffraction grating or refracting prism which spatially disperses the spectrum
Data Source
AI summary
A calibration device receives at least a first multispectral measurement of: a first monochromatic signal taken at a first pixel location; a second multispectral measurement of a second monochromatic signal taken at a second pixel location; and a multiplicity of third multispectral measurements of a spatially distributed wide bandwidth dispersed spectrum, of a wide bandwidth signal, taken at a multiplicity of third pixel locations. The device relates known pixel values of wavelengths to pixel values of measured wavelengths. The device outputs spectrum wavelength and power calibration values for the multispectral imaging system, comprising at least a relation of: a first third pixel location to a first known wavelength; and a second third pixel location to a second known wavelength.