Sequential Gain Control for Accurate White Balance
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Solution Overview
Problem
Electronic still cameras with auto white balance functions face issues in accurately determining white subjects, leading to 'drawing effects' where white subjects appear bluish and red subjects appear light red, resulting in inappropriate white balance in recorded images.
Innovation Solution
An image pickup apparatus with first and second amplifying units for color components, a gain value storage unit, and control units to vary and set gain values for maintaining white balance, allowing for accurate detection and selection of gain values to correct white balance in real-time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a simple white detection method is used to determine white subjects, then the processing speed is fast, but the accuracy of white balance determination deteriorates, causing drawing effects where white subjects appear bluish and red subjects appear light red
Solution Approach 1:
The patent applies preliminary action by pre-storing multiple types of gain values in a storage unit before actual image capture. These gain values are prepared in advance for different color components (R, G, B) and are used sequentially during white balance adjustment, eliminating the need for complex real-time calculations while maintaining high accuracy in white subject detection
Solution Approach 2:
The patent implements dynamics by sequentially varying gain values for different color components through a varying unit. Instead of using fixed gain values, the system dynamically adjusts R, G, and B gain values in sequence based on detected white subject information, allowing adaptive optimization of white balance accuracy without increasing overall system complexity
2Measurement precision
If gain values are adjusted in real-time for accurate white balance, then the white balance accuracy is improved, but the processing time and computational load increase
Solution Approach 1:
The system performs preliminary preparation by storing multiple gain value types in advance. During actual operation, the control unit simply selects and applies pre-computed gain values from the storage unit, avoiding time-consuming real-time calculations while maintaining accurate white balance adjustment
Solution Approach 2:
The patent segments the gain adjustment process into distinct sequential steps for different color components (R, G, B). Each color component's gain is adjusted independently in sequence based on white subject detection results, reducing computational complexity and processing time compared to simultaneous multi-channel adjustment
3Measurement precision
If sequential gain variation is performed for multiple color components, then the white balance accuracy is improved, but the control system complexity increases
Solution Approach 1:
The patent merges the functions of multiple gain adjusting circuits into a single integrated control system. The control unit sequentially controls gain values for R, G, and B components through unified control logic, and the adding unit combines detection results from all color components to generate comprehensive white subject information, reducing overall system complexity
Data Source
AI summary
A first gain value table stores gain values set in R and B amplifiers of a first gain adjusting circuit, and a second gain value table stores gain values set in R and B amplifiers of a second gain adjusting circuit. The gain values from the second gain value table are sequentially set in the second gain adjusting circuit to detect white portions. Based on the detection of the white portions, a gain value to be set in the first gain adjusting circuit is selected from the first gain value table, to obtain an image that maintains white balance.