Chroma Signal Gradation Restoration Using Brightness Guide
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Solution Overview
Problem
Existing techniques for producing High Dynamic Range (HDR) images from images captured with different sensitivities, particularly color images, often result in degraded gradation, especially when the camera sensitivity is low, leading to reduced image quality.
Innovation Solution
An image processing apparatus that includes a gradation control part which obtains a brightness signal from a black-and-white image and a chroma signal from a color image, and uses this information to adjust the gradation of the chroma signal, thereby enhancing the image quality by aligning and synthesizing the images captured with varying sensitivities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If images are captured with different sensitivities to produce HDR images, then the dynamic range is improved, but the gradation of the color image is degraded
Solution Approach 1:
The patent uses the brightness signal as an intermediary guide to transfer gradation information from the high-sensitivity black-and-white image to the low-sensitivity color image. The brightness signal acts as a mediator that carries the gradient characteristics needed to restore chroma signal quality without requiring the color camera to have high sensitivity itself.
Solution Approach 2:
The patent applies parameter changes by adjusting the chroma signal based on the brightness signal's gradient characteristics. Specifically, it modifies the chroma signal parameters (color information) using the brightness signal's spatial gradient data to restore gradation quality while maintaining the HDR dynamic range benefits.
2Device complexity
If the sensitivity of the color camera is reduced, then the device complexity is reduced, but the image quality is degraded
Solution Approach 1:
The patent merges the strengths of two different camera systems: a high-sensitivity black-and-white camera for brightness information and a lower-sensitivity color camera for chroma information. By combining these two imaging paths and processing their outputs together, the system achieves high-quality HDR images without requiring the color camera to be complex or highly sensitive.
Solution Approach 2:
The brightness signal serves as an intermediary that transfers the high-precision gradient information from the black-and-white imaging system to guide the restoration of the chroma signal from the color imaging system, enabling quality recovery without increasing color camera complexity.
Data Source
AI summary
An image processing apparatus is provided to alleviate degradation of the gradation of a color image in the case where images having a sensitivity different from each other are obtained by imaging one same object in black-and-white and color. The image processing apparatus includes a gradation control part obtaining a brightness signal representing a black-and-white image and a chroma signal representing a color image obtained by imaging a same object as that for the black-and-white image and that controls gradation of the chroma signal on the basis of the brightness signal. This configuration can suppress degradation of the gradation of a color image to be minimal in the case where images having a sensitivity different from each other are obtained by imaging one same object in black-and-white and color.