Camera Module White-Balance Patch for White LED Spectrum Compensation
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Solution Overview
Problem
Current camera module control systems are inadequate for handling the unique characteristics of white LEDs used as flashes in portable electronic devices, particularly due to their deviation from the blackbody curve in chromaticity charts and variability in color spectra, leading to insufficient white-balancing and exposure control.
Innovation Solution
The system employs a processor-controlled white-balance patch that redefines the reference white region on a chromaticity chart, allowing for alternate minimum and maximum values and instructions to accommodate the color coordinates of white LEDs, enabling more precise white-balancing and exposure control by scanning multiple images with a white LED flash.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If standard white-balancing algorithms are used with white LED flash, then the system can handle traditional light sources (xenon, incandescent, fluorescent) that follow the blackbody curve, but it fails to accurately compensate for white LED's unique color spectrum characteristics
Solution Approach 1:
The patent modifies the reference white region parameters in the chromaticity chart to accommodate white LED's color coordinates. Specifically, it adjusts the minimum and maximum values of the reference white region and modifies the locus (error term) to create an expanded region that encompasses white LED's spectrum characteristics, thereby enabling accurate white-balancing for white LED while maintaining compatibility with traditional light sources
Solution Approach 2:
The system dynamically adjusts the reference white region parameters based on the detected light source type. When white LED is detected, the system switches to using the modified reference white region with adjusted minimum/maximim values and locus, whereas traditional light sources use the standard reference white region, thus adapting the white-balancing algorithm to the specific light source characteristics
2Reliability
If the reference white region is constrained to follow the blackbody curve, then algorithms work well for traditional light sources, but white LED's color coordinates fall outside this region causing white-balancing failures
Solution Approach 1:
The patent segments the reference white region into multiple zones: the original blackbody curve-based region for traditional light sources, and an expanded region incorporating white LED's color coordinates. This segmentation allows the system to maintain reliable white-balancing for blackbody light sources while simultaneously accommodating white LED's unique characteristics
Solution Approach 2:
The patent introduces an intermediary mechanism (the modified reference white region with adjusted locus and minimum/maximim values) that bridges between the traditional blackbody curve constraint and white LED's color coordinates. This intermediary expanded region serves as a transition zone that allows both traditional and LED light sources to be accommodated within a unified white-balancing framework
3Stability of the object's composition
If minimum and maximum values for the reference white region are strictly enforced, then white-balancing is stable for traditional sources, but white LED's varying color spectra are rejected as out-of-range
Solution Approach 1:
The patent changes the minimum and maximum value parameters that define the reference white region boundaries. By increasing these bounds and adjusting the locus (error term), the system creates a more permissive reference white region that maintains stability for traditional light sources while accommodating the varying color spectra of white LED without rejecting them as out-of-range
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 allows for effective white-balancing and exposure control with white LEDs, compensating for their changing light levels and spectra, ensuring accurate image capture by redefining the reference white region and refining initial values across successive images.
Implementation Method 1
a white LED 207 serving as a flash for taking pictures
Implementation Method 2
the spectrums of light emitted by each of them, despite being different, provide a range of light frequencies that resemble the expected behavior of radiant emissions of a blackbody at given temperatures
Data Source
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AI summary
A method and an apparatus enabling use of a light source emitting a spectrum of light not following characteristics of a blackbody source of light with a camera module programmed for use with light sources following characteristics of blackbody sources of light, wherein a white-balance patch is transmitted to the camera module to cause the camera module to accept color coordinates representing a point on a chromaticity chart that partly defines a region of color coordinates on the chromaticity chart into which color coordinates of the light source fall and to which color coordinates of a reference white color derived by a white-balance routine of the camera module are constrained.