Ramp ADC Nonlinear Signal Segmentation for HDR Memory Reduction
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Solution Overview
Problem
Conventional image sensors require more time and memory to capture high-quality high dynamic range (HDR) frames due to the need to capture and process two frames with different exposure levels, resulting in increased image capturing and processing time and larger memory requirements.
Innovation Solution
An electronic device with an image sensor and a ramp analog to digital converter that generates non-linear ramp signals to produce most significant bit and least significant bit data for pixels, allowing for the combination of these data into a single frame data set, thereby reducing memory usage without compromising image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional image sensors capture two frames with different exposure levels to obtain high dynamic range, then image quality is improved, but memory size and processing time increase
Solution Approach 1:
The patent segments the 10-bit image data into two parts: most significant bits (MSBs) and least significant bits (LSBs). The MSBs are captured during a first exposure period and stored in memory, while the LSBs are captured during a second exposure period. This segmentation allows the system to achieve HDR效果 without storing complete high-bit-depth data for both frames, thereby reducing memory requirements while maintaining image quality.
Solution Approach 2:
The patent changes the exposure time parameter by capturing MSBs during a first exposure period and LSBs during a second exposure period with different exposure durations. This parameter change enables the sensor to capture both bright and dark areas of the scene effectively, achieving high dynamic range while optimizing memory usage by only storing necessary bit portions.
2Measurement precision
If conventional image sensors capture two frames with different exposure levels, then high dynamic range is achieved, but image capturing time increases
Solution Approach 1:
The patent performs preliminary action by capturing and storing the most significant bits (MSBs) during a first exposure period before capturing the least significant bits (LSBs) in a second exposure period. This preliminary capture of the most important data reduces the processing burden later and allows for more efficient HDR frame generation, thereby reducing overall processing time while maintaining high dynamic range quality.
Solution Approach 2:
By segmenting the image data capture into two phases (MSB capture and LSB capture) with different exposure times, the patent enables parallel processing opportunities and reduces the total time required for HDR frame generation compared to capturing and processing two complete high-resolution frames.
3Measurement precision
If conventional image sensors store complete frame data for processing, then image quality is maintained, but processing time increases
Solution Approach 1:
The patent extracts only the necessary portions of image data (MSBs and LSBs separately) instead of storing and processing complete high-bit-depth frames. By extracting and storing only the essential bit portions in memory, the system significantly reduces the amount of data requiring processing while maintaining the quality needed for HDR frame generation, thereby improving processing efficiency and productivity.
Data Source
AI summary
An electronic device and an image capture method are provided. The electronic device includes an image sensor, a ramp analog to digital converter, and a memory. The image sensor includes a plurality of pixel units arranged in an array, and the pixel units output a plurality of first image capturing signals and a plurality of second image capturing signals in an image capturing operation. The ramp analog to digital converter generates a plurality of most significant bit data corresponding to a plurality of pixels according to a first nonlinear ramp signal and the first image capturing signals, and generates a plurality of least significant bit data corresponding to the plurality of pixels according to a second nonlinear ramp signal and the second image capturing signals. The memory stores the most significant bit data of these pixels and the least significant bit data of these pixels together to generate frame data.