Image Sensor Bidirectional Readout for Flash Latency
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Solution Overview
Problem
Existing methods for improving image quality when using a flash with rolling shutter image sensors are inefficient due to latency and memory usage, often resulting in suboptimal image generation.
Innovation Solution
The method involves reading out first and second lines of pixels in alternating sequences in opposite directions and interleaving the data to create a single image, allowing for simultaneous exposure and readout, thereby reducing the total time to read out the pixel array and improving image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If two separate images are captured (one with flash, one without flash) and combined, then image quality can be improved, but latency increases and memory usage increases
Solution Approach 1:
The image sensor array is segmented into first lines and second lines that are read out in opposite directions. This segmentation allows simultaneous capture of flash and no-flash images across different line groups, eliminating the need to capture two complete images sequentially and thereby reducing latency while maintaining image quality.
Solution Approach 2:
The readout operation continues simultaneously in both directions across the sensor array during a single exposure period. First lines are read out in one direction while second lines are read out in the opposite direction at the same time, ensuring continuous useful action throughout the exposure period and eliminating idle time between capturing flash and no-flash images.
2Manufacturing precision
If two separate images are captured (one with flash, one without flash) and combined, then image quality can be improved, but memory usage increases
Solution Approach 1:
By segmenting the sensor array into first and second lines with opposite readout directions, the patent captures flash and no-flash data simultaneously during a single exposure. This eliminates the need to store two complete separate images in memory, reducing memory usage while still enabling image quality improvement through selective line combination.
Solution Approach 2:
The patent merges the readout of first lines and second lines into a single simultaneous operation during one exposure period. By combining the data from both line groups in real-time during the single exposure, the system avoids the need to store separate complete images, thereby reducing memory requirements while maintaining the ability to generate high-quality images.
3Device complexity
If all lines are read out in a single direction sequentially, then the readout process is simple, but the total readout time increases
Solution Approach 1:
The patent introduces a bidirectional readout dimension by reading first lines in one direction and second lines in the opposite direction simultaneously. This dimensional change from unidirectional to bidirectional readout allows parallel processing of different line groups, effectively halving the total readout time while adding manageable complexity through symmetric control logic.
Solution Approach 2:
The readout system dynamically switches between reading different line groups in opposite directions based on the exposure timing. During the exposure period, the system dynamically coordinates multiple readout operations in opposite directions, optimizing the use of available time and reducing total readout duration while maintaining manageable complexity through systematic control.
Data Source
AI summary
A method comprising reading out first lines of pixels of a sensor, when the first lines are read out in a sequence of the first lines in a first direction along the sensor also reading out different second lines of the pixels of the sensor, when the second lines are read out in a sequence of the second lines in a different second direction along the sensor and interleaving the read outs from the first lines of pixels and the different second lines of pixels.