Luminance Correction and Image Composition for Flicker-Free HDR Imaging
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Solution Overview
Problem
Existing image sensing devices face challenges in capturing images with varying exposure times and gains, leading to flicker phenomena and image distortion, particularly in high-performance applications such as smartphones, digital cameras, and medical micro cameras.
Innovation Solution
An image processing device that includes a gain control circuit to adjust image brightness, a luminance correction circuit to replace pixel values based on relative brightness, and an image composition circuit to combine images using color-specific brightness thresholds, addressing issues of flicker and distortion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If images are captured with different exposure times and gains, then image brightness and dynamic range are improved, but flicker phenomena and image distortion occur
Solution Approach 1:
The patent segments the image processing into multiple independent circuits: gain control circuit for brightness adjustment, luminance correction circuit for distortion correction, and image composition circuit for final synthesis. Each circuit processes specific aspects of image data separately, allowing optimized handling of different exposure conditions without introducing flicker or distortion artifacts.
Solution Approach 2:
The patent dynamically adjusts multiple parameters including gain values, exposure times, and luminance correction factors based on the captured image data. The gain control circuit modifies gain values to compensate for different exposure conditions, while the luminance correction circuit applies correction factors to eliminate distortion, thereby maintaining image quality stability across varying brightness conditions.
2Illumination intensity
If gain is increased to brighten dark images, then image brightness is improved, but noise and distortion increase
Solution Approach 1:
The patent applies preliminary gain control to brighten dark regions before the main image processing. The gain control circuit预先 adjusts the gain values based on the relationship between first and second input images, enabling brightness enhancement while minimizing the introduction of noise and distortion artifacts in subsequent processing stages.
Solution Approach 2:
The luminance correction circuit acts as an intermediary between the gain control and final image composition. It receives the gain-adjusted image data and applies additional luminance correction to compensate for distortion and noise introduced during gain adjustment, thereby producing cleaner final images.
3Adaptability or versatility
If multiple images with different exposure times are processed, then dynamic range is improved, but processing complexity increases
Solution Approach 1:
The patent divides the complex processing task into three dedicated circuits: gain control circuit for brightness adjustment, luminance correction circuit for distortion correction, and image composition circuit for final synthesis. This segmentation allows each circuit to handle specific aspects of multi-exposure image processing independently, reducing overall processing complexity while maintaining enhanced dynamic range capability.
Solution Approach 2:
The image composition circuit serves multiple functions: it composites images from different exposure times, applies color-specific brightness adjustments, and integrates luminance correction results. This multi-functionality reduces the need for separate processing stages, thereby reducing overall device complexity while maintaining versatile dynamic range processing capability.
Data Source
AI summary
An image processing device is provided to comprise: a luminance correction circuit configured to receive a first image and a second image of a target scene or object and generate a third image by selectively replacing the second image with the first image based on a relationship between pixel values at a same position in the first image and the second image; and an image composition circuit communicatively coupled to the luminance correction circuit to receive the first image and the third image and configured to generate a fourth image by composing the first image and the third image based on a color-specific brightness value of the first image or the third image and threshold values associated with each color.