Image Processing Apparatus Chromatic Adaptation
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Solution Overview
Problem
Conventional image processing methods fail to accurately reproduce the visual appearance of an image under varying light sources, particularly due to incomplete chromatic adaptation, resulting in unnatural-looking corrected images.
Innovation Solution
An image processing apparatus and method that estimates the capturing light source and performs color balance correction considering human visual characteristics, including incomplete chromatic adaptation, to faithfully reproduce the atmosphere of the captured image.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If color balance correction is performed using conventional methods, then the image can be corrected, but the visual appearance under varying light sources cannot be accurately reproduced
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the adaptation rate parameter based on the estimated color temperature of the capturing light source. The adaptation rate is set to different values depending on whether the color temperature is 5000K or higher (indicating daylight) or lower (indicating artificial light), thereby optimizing color balance correction for different lighting conditions to accurately reproduce visual appearance.
2Measurement precision
If chromatic adaptation is considered in color balance correction, then the visual characteristic can be improved, but the complexity of the processing increases
Solution Approach 1:
The patent manages processing complexity by using a simplified parameter-based approach rather than complex computational models. The adaptation rate is determined through straightforward parameter selection based on color temperature thresholds, avoiding the need for complex chromatic adaptation algorithms while still achieving accurate visual appearance reproduction.
3Measurement precision
If the adaptation rate is set high for accurate color reproduction, then the visual appearance is faithfully reproduced, but the natural look under artificial light is compromised
Solution Approach 1:
The patent resolves this contradiction by dynamically changing the adaptation rate parameter based on the capturing light source characteristics. When the color temperature indicates artificial light (lower than 5000K), the adaptation rate is set to a lower value that preserves natural appearance. When daylight is detected (5000K or higher), a higher adaptation rate is applied for accurate color reproduction, thus avoiding unnatural appearance while maintaining accuracy where appropriate.
Data Source
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AI summary
An image processing apparatus (100) which corrects color balance of an image in image data captured by an image capturing apparatus having a color balance correction function, the apparatus comprising: a light source estimation means (204) configured to estimate a capturing light source of the image based on a color value; a first color conversion means (205) configured to perform first color conversion of converting, based on the capturing light source and the color value, the image into an image in which color balance correction applied depending on the image capturing apparatus that has captured the image data containing the image is weakened; and a second color conversion means (206) configured to perform second color conversion for the image having undergone the first color conversion, by using an adaptation rate corresponding to a color value defined based on chromatic adaptation of a man under the capturing light source.