White Balance Stabilization via Dual-Sensor Light Source Reliability
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Solution Overview
Problem
Conventional white balance adjustment in imaging devices is unstable due to changes in the background captured, especially when a moving object is imaged with a narrow view angle, leading to variations in white balance settings.
Innovation Solution
An image processing device that uses a white balance setting unit to determine a white balance adjustment value based on both the image signal from an imaging element and a sensor signal from an optical sensor with a wider view angle and different spectral sensitivity, classifying light sources and assessing the reliability of the estimation results to stabilize the adjustment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If white balance adjustment is performed based on subject light of the captured image with a narrow view angle, then the white balance adjustment can be performed with higher precision for the captured subject, but the background captured in the image changes largely causing instability in white balance adjustment
Solution Approach 1:
The patent segments the light source detection function into two parts: the imaging element captures the subject with narrow view angle for precise white balance adjustment, while the optical sensor unit with wider view angle captures the overall lighting environment. This segmentation allows each component to perform its specialized function, resolving the contradiction between precision and stability.
Solution Approach 2:
The optical sensor unit acts as an intermediary that detects the spectral characteristics of the imaging environment with a wider view angle. Its detection results are used to determine the reliability of the light source estimation from the imaging element, serving as a mediator to stabilize the white balance adjustment when the background changes.
2Reliability
If the optical sensor unit has a wider view angle than the captured image, then the spectral characteristic of the imaging environment can be detected more reliably, but the device complexity increases
Solution Approach 1:
The optical sensor unit is designed to perform multiple functions: it detects the spectral characteristics of the imaging environment, estimates the light source type, and determines the reliability of the imaging element's light source estimation. This multi-functionality reduces the need for additional dedicated components, thereby limiting the increase in device complexity while improving reliability.
Solution Approach 2:
The patent changes the spectral sensitivity parameters of the optical sensor unit to be different from the imaging element, with enhanced sensitivity in the infrared region. This parameter change allows the optical sensor unit to detect spectral characteristics that are not visible to the imaging element, improving light source estimation reliability without requiring a completely different sensor system.
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 enables more accurate and stable white balance adjustment by comparing light-source estimation results from both signals, preventing adjustments based on unreliable changes in the background, thus maintaining consistent color balance.
Implementation Method 1
an image signal of a captured image generated by photoelectrically converting light from a subject by an imaging element
Implementation Method 2
a second photoelectric conversion signal obtained by photoelectrically converting the subject light by the optical sensor having a second spectral sensitivity characteristic
Data Source
AI summary
An imaging unit 23 generates an image signal of a captured image. An optical sensor unit 25 generates a sensor signal that has a wider view angle than that of the imaging unit 23 and is according to a spectral characteristic upon obtaining the captured image. A controller 50 determines reliability of a light-source estimation result based on the image signal generated by the imaging unit 23, using a light-source estimation result based on the sensor signal generated by the optical sensor unit 25. For example, the controller 50 classifies the light-source estimation result based on the image signal into categories of light sources capable of being estimated based on the sensor signal, and compares the category into which the light-source estimation result is classified with the light source estimated based on the sensor signal. In a case where the light source estimated based on the sensor signal is not changed when the category into which the light-source estimation result is classified is changed, it is determined that the light-source estimation result based on the image signal is not reliable, and an adjustment value of white balance adjustment is not updated. Then, the white balance adjustment can accurately and stably be performed.