Digital Camera White Balance Self-Calibration Using Correlated Color Temperature

Solution Overview

Problem

The manufacturing process of digital camera devices is hindered by the need to measure each camera sensor's response, which adds time and cost, and existing calibration techniques require prior knowledge of the sensor response.

Innovation Solution

The implementation of automatic self-calibration techniques that initiate calibration based on operating conditions, accumulate data on correlated color temperature, calculate CCT vectors, and generate gray point correction factors, allowing for calibration without prior sensor response knowledge and enabling the use of lower quality camera sensors.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If every camera sensor is measured during manufacturing to obtain sensor response information, then proper white balance calibration can be achieved, but manufacturing time and cost increase significantly

Engineering Contradiction:

Improvesensor response measurement accuracyVSAvoidmanufacturing throughput

Core Design Contradiction:

Measurement precisionVSProductivity

Solution Approach 1:

The camera device performs self-calibration using the formula rgb_corrected = rgb * correction_factors, where the device uses its own captured images and calculated CCT values to determine correction factors, eliminating the need for external measurement equipment and manual measurement processes during manufacturing

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The patent transforms the calibration approach from sensor-specific physical measurements to a mathematical parameter-based system using correlated color temperature (CCT) and correction factors that can be calculated from image data, allowing calibration without direct sensor response measurement

Inventive Principle:

Principle #35Parameter changes

2Measurement precision

If every camera sensor is measured during manufacturing to obtain sensor response information, then accurate white balance calibration can be achieved, but manufacturing cost increases

Engineering Contradiction:

Improvesensor response measurement accuracyVSAvoidmanufacturing cost

Core Design Contradiction:

Measurement precisionVSEase of manufacture

Solution Approach 1:

The camera device performs self-calibration using the formula rgb_corrected = rgb * correction_factors, where the device uses its own captured images and calculated CCT values to determine correction factors, eliminating the need for external measurement equipment and manual measurement processes during manufacturing

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The patent transforms the calibration approach from sensor-specific physical measurements to a mathematical parameter-based system using correlated color temperature (CCT) and correction factors that can be calculated from image data, allowing calibration without direct sensor response measurement

Inventive Principle:

Principle #35Parameter changes

3Ease of manufacture

If camera sensors with high variation are used to reduce cost, then manufacturing cost decreases, but white balance calibration becomes difficult without prior sensor response knowledge

Engineering Contradiction:

Improvemanufacturing costVSAvoidcalibration adaptability

Core Design Contradiction:

Ease of manufactureVSAdaptability or versatility

Solution Approach 1:

The patent transforms the calibration approach from sensor-specific physical measurements to a mathematical parameter-based system using correlated color temperature (CCT) and correction factors that can be calculated from image data, allowing calibration without direct sensor response measurement

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The system uses feedback from captured images to calculate CCT values and determine correction factors, continuously adapting the calibration based on actual performance data captured during device operation rather than relying on pre-manufacturing sensor characteristics

Inventive Principle:

Principle #23Feedback

Data Source

PatentUS8004566B2Self calibration of white balance for a digital camera device using correlated color temperature data

Publication Date: 2011.08.23 QUALCOMM INC

AI summary

This disclosure describes automatic self-calibration techniques for digital camera devices. In one aspect, a method for performing a calibration procedure in a digital camera device comprises initiating the calibration procedure when a camera sensor of the digital camera device is operating, accumulating data for the calibration procedure, the data comprising one or more averages of correlated color temperature (CCT) associated with information captured by the camera sensor, calculating one or more CCT vectors based on the one or more averages of CCT, and generating gray point correction factors based on the one or more CCT vectors.