Automatic White Balance Calibration Using Sensor Histogram Compensation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Image capture devices struggle to automatically adapt to varying illumination conditions, leading to unrealistic color casts in digital images, necessitating effective white balance techniques to accurately represent colors.
Innovation Solution
The implementation of an automatic white balance (AWB) method that uses calibrated references generated under different color temperatures, both simulated and natural lighting conditions, and adjusts histograms to account for individual imaging sensor variations, ensuring accurate color temperature estimation and correction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If automatic white balance techniques are applied to compensate for illumination color, then color accuracy is improved, but device complexity increases due to the need for calibrated references and histogram adjustments
Solution Approach 1:
The patent applies preliminary action by pre-calibrating references under different color temperatures before actual image capture. The system stores these pre-computed references and uses them during white balance processing, avoiding the need to perform complex calibration computations in real-time, thus improving color accuracy while managing processing complexity.
Solution Approach 2:
The patent utilizes parameter changes by adjusting histogram parameters and color temperature values based on pre-calibrated references. The system modifies image parameters (color channels, brightness) according to the selected reference that best matches the illumination conditions, achieving accurate color compensation through controlled parameter transformations.
2Adaptability or versatility
If calibrated references under multiple color temperatures are used, then white balance accuracy across diverse lighting conditions is improved, but the quantity of data and processing requirements increase
Solution Approach 1:
The patent applies segmentation by dividing the continuous spectrum of color temperatures into discrete segments or categories (e.g., different lighting conditions like daylight, tungsten, fluorescent). The system creates separate calibrated references for each segment, allowing the image processor to select the most appropriate reference based on the detected lighting condition, thereby achieving broad adaptability with a manageable set of reference data.
3Manufacturing precision
If histogram adjustments are made to account for sensor variations, then manufacturing precision across different sensors is improved, but the complexity of calibration and adjustment increases
Solution Approach 1:
The patent applies copying by creating a master set of calibrated references from a reference sensor and then copying/adapting these references for use with individual sensors. The system uses histogram adjustment to replicate the reference sensor's color characteristics across different sensors, accounting for manufacturing variations without requiring each sensor to undergo complex individual calibration procedures.
Data Source
AI summary
A method for calibrating automatic white balance (AWB) in a digital system is provided that includes capturing an image of a test target under a natural lighting condition, generating a first color temperature reference from the captured image, and outputting AWB configuration data for the digital system, wherein the AWB configuration data comprises the first color temperature reference and a second color temperature reference generated using the test target under simulated lighting conditions. A method for calibrating automatic white balance (AWB) in a digital system comprising a first imaging sensor is provided that includes receiving a reference for AWB that was generated using an image captured using a second imaging sensor, and compensating a histogram reference into a histogram reference for AWB for the first imaging sensor in the digital system based on R, G, B adjustment values from the second imaging sensor to the first imaging sensor.