Image Sensor High Dynamic Range Readout Timing Control
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Solution Overview
Problem
Existing methods for reading out high dynamic range image frames in image sensors are inefficient, requiring two time cycles to complete data reading and adjusting frame length, which can lead to non-constant frame rates and inability to output images with random integration times, failing to meet NTSC or PAL frame rate requirements.
Innovation Solution
A method that determines specific start times for integration and reading cycles for both current and next image frames, allowing for constant frame length and efficient resetting and reading of pixel arrays, with separate integration times for each frame, ensuring correct and complete image output with constant frame rate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the pixel array is reset row by row for both first and second integration treatments sequentially, then the HDR image data can be obtained, but the frame length must be adjusted which causes non-constant frame rate
Solution Approach 1:
The patent applies preliminary action by determining the start time of the second integration treatment cycle before the first integration treatment is completed. Specifically, the start time of the second integration treatment is set to occur at frame length L minus the second integration time T2, allowing the pixel array to be prepared for the second integration before the first integration finishes, thus avoiding frame length adjustment and maintaining constant frame rate.
2Reliability
If the frame length is adjusted to accommodate sequential reset and readout operations, then all integration treatments can be completed, but the output frame rate becomes non-constant
Solution Approach 1:
The patent applies dynamics by making the timing of the second integration treatment adaptive rather than fixed. The start time of the second integration treatment is dynamically determined based on the relationship between frame length L and second integration time T2, specifically starting at L-T2. This dynamic timing allows the system to complete all integration treatments while maintaining a constant frame output rate, resolving the contradiction between treatment completion and frame rate stability.
3Productivity
If the pixel array is reset for the next image frame after current frame processing, then continuous frame output is achieved, but integration times cannot be random
Solution Approach 1:
The patent applies segmentation by dividing the frame processing into distinct first and second integration treatment cycles with independently controllable start times. The first integration treatment starts at time 0, while the second integration treatment starts at L-T2. This segmentation allows each integration cycle to be independently timed, enabling continuous frame output while maintaining the ability to use random integration times for HDR capture.
Data Source
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AI summary
A method for reading out a high dynamic range image frame in an image sensor and a device using the same are provided. The image sensor comprises a pixel array with a plurality of pixels arranged in columns and rows. The device comprises a pixel array comprising a plurality of pixels arranged in columns and rows; a calculating unit, configured to calculate and determine a first integration time and a second integration time according to an output image frame information; and an integration time processing unit.