Image Processor Sub-pixel Exposure Segmentation for Flicker Reduction
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Solution Overview
Problem
High Dynamic Range Imaging (HDRI) techniques face challenges in reducing flicker effects due to variations in pixel values caused by image capture timing, particularly when capturing images with short exposure times, leading to artifacts like LED flicker phenomena.
Innovation Solution
An image processor acquires and processes pixel values from images captured at different exposure times, using a configuration of sub-pixels with varying exposure times, and applies correction and synthesis techniques to generate a high dynamic range image while minimizing flicker effects by outputting pixel values that account for saturation and timing variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a short exposure time is used to capture images, then the ability to capture fast-moving objects and reduce motion blur is improved, but flicker artifacts and pixel value variations occur due to timing sensitivity
Solution Approach 1:
The image sensor is divided into multiple sub-pixels with different exposure times (first sub-pixels with longer exposure time, second sub-pixels with shorter exposure time). This segmentation allows the system to capture both fast-moving objects (using short exposure sub-pixels) and maintain stable pixel values (using long exposure sub-pixels) simultaneously, resolving the contradiction between capture speed and pixel value stability.
2Illumination intensity
If High Dynamic Range Imaging is performed by synthesizing long and short exposure images, then the dynamic range is improved, but flicker effects and LED flicker phenomena become more prominent
Solution Approach 1:
Different regions (sub-pixels) of the image sensor are assigned different exposure times based on their specific function. First sub-pixels with longer exposure times are used for capturing dim light sources to expand dynamic range, while second sub-pixels with shorter exposure times are used for capturing bright light sources where flicker would be problematic. This local differentiation allows HDR synthesis while minimizing flicker artifacts in the final image.
Data Source
AI summary
An image processor according to the present embodiment includes an acquirer, an output unit, and a generator. The acquirer acquires a first pixel value obtained by making a pixel value in a first image captured in a first exposure time correspond to a predetermined sensitivity and a second pixel value obtained by making a pixel value in a second image captured in a second exposure time shorter than the first exposure time correspond to the predetermined sensitivity. The output unit outputs a pixel value serving as a predetermined value larger than the second pixel value when the first pixel value has been saturated and the second pixel value corresponding to the first pixel value is less than the first pixel value. The generator generates a high dynamic range image using at least the first image and the second image based on the pixel value output by the output unit.