Image Sensor Pre-Processor for HDR Dynamic Range Extension
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Solution Overview
Problem
Image sensors have a narrower dynamic range than the human eye, leading to discrepancies in captured images, especially in backlight conditions, which existing HDR technologies do not adequately address.
Innovation Solution
An image sensor with a pre-processor that generates multiple images with different exposure times and merges them to increase dynamic range, supplemented by an image processor that determines the mode of merging based on image information, including real-time HDR processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If HDR processing is performed in the image processor, then the dynamic range of the output image is improved, but the processing load and complexity of the image processor increases
Solution Approach 1:
The HDR processing function is segmented from the image processor and relocated to the image sensor's pre-processor. This divides the overall image processing system into distinct functional modules, with the pre-processor handling HDR merging and the image processor handling subsequent processing tasks, thereby reducing the processing load on the image processor.
Solution Approach 2:
HDR processing is performed as a preliminary action before the image data is transmitted to the image processor. The pre-processor merges multiple images with different exposure times and generates the merged image in advance, so that the image processor receives pre-processed data requiring less computational effort.
2Reliability
If multiple images with different exposure times are captured, then the dynamic range is extended, but the processing time and complexity of merging these images increases
Solution Approach 1:
The pre-processor performs HDR merging operations in advance within the image sensor, utilizing the captured images with different exposure times to generate a merged image before transmission. This preliminary merging action reduces the overall processing time by eliminating the need for post-capture merging operations.
Solution Approach 2:
The pre-processor acts as an intermediary component between the image sensor and the image processor. It receives multiple exposure images, performs the time-consuming merging operation, and outputs the merged image, thereby mediating the time complexity between image capture and final processing.
3Reliability
If HDR processing is performed externally, then the dynamic range is improved, but the signal-to-noise ratio may deteriorate due to additional processing steps
Solution Approach 1:
The image sensor's pre-processor performs HDR merging on the raw image data directly from the sensor, enabling the system to serve itself with high-quality merged images. This self-service approach preserves the original signal characteristics and minimizes noise introduction that would occur with external processing of already-converted data.
Solution Approach 2:
HDR merging is performed preliminarily on the raw sensor data before any additional processing or conversion that might degrade signal quality. By conducting the merging operation at this early stage, the system maintains optimal signal-to-noise ratio while achieving extended dynamic range.
Data Source
AI summary
An image sensor includes a sensing unit configured to generate a plurality of images having different exposure times for a same object, a pre-processor configured to generate a merged image by merging the plurality of images, an interface circuit configured to output at least one of the plurality of images and/or the merged image to an external processor, and a controller configured to control the pre-processor to selectively generate the merged image based on information of the plurality of images.