Image Processing Apparatus White Balance Correction Multiple Light Sources
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Solution Overview
Problem
Conventional automatic white balance control in imaging apparatuses struggles to achieve appropriate color tints for multiple light sources, particularly when flash light and ambient light sources with different color temperatures are present, leading to unsuitable white balance and inappropriate color reproduction.
Innovation Solution
An image processing apparatus that generates first and second developed image data using specific white balance correction values for each light source, calculates a combining ratio based on color evaluation values, and combines these images to produce an image with appropriate tints for both light sources, ensuring accurate color representation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If automatic white balance control calculates a single white balance coefficient from the entire screen and applies it uniformly, then the processing is simple and fast, but the color reproduction becomes inaccurate when multiple light sources with different color temperatures are present
Solution Approach 1:
The image screen is divided into multiple blocks, and each block is independently analyzed to determine its dominant light source characteristics. This segmentation allows different white balance coefficients to be calculated for different regions, resolving the contradiction by enabling accurate color reproduction for multiple light sources while maintaining efficient block-based processing
Solution Approach 2:
Different white balance coefficients are applied to different blocks based on their local light source characteristics. Instead of using a single uniform coefficient for the entire screen, each block receives a customized coefficient that matches its specific lighting conditions, thereby achieving accurate color reproduction across diverse lighting environments
2Adaptability or versatility
If the white balance is adjusted to the middle between multiple light sources, then a compromise is achieved, but both regions irradiated with different light sources become tinged with inappropriate colors
Solution Approach 1:
The image is segmented into blocks, and each block is assigned a white balance coefficient appropriate to its specific light source. This prevents the compromise effect by allowing each region to have its own optimized white balance setting rather than forcing a middle-ground solution
Solution Approach 2:
Each block receives a white balance coefficient tailored to its local lighting conditions. Regions illuminated by different light sources (e.g., flash vs. ambient light) are processed with different coefficients, ensuring accurate color reproduction for each region without cross-contamination of color tints
Data Source
AI summary
The present invention generates first developed image data by correcting image data with use of a first white balance correction value corresponding to a first light source, generates second developed image data by correcting the image data with use of a second white balance correction value corresponding to a second light source, calculates a color evaluation value of each of blocks by adding and averaging color evaluation values of pixels in the image data for each of the divided blocks, calculates a combining ratio based on a difference between the calculated color evaluation value of each of the blocks and a color evaluation value of white under the second light source, and combines the first developed image data and the second developed image data according to the calculated combining ratio.