Image Sensor Control Circuit for HDR and Linear Mode Switching
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Solution Overview
Problem
Current image sensors face limitations in automatic mode switching due to poor scene adaptation, relying solely on luminance, which makes manual switching impractical and limits the effectiveness of automatic switching algorithms.
Innovation Solution
A control circuit and method that includes a statistical circuit to generate luminance statistical data and an auto-exposure circuit to set target luminance, with a calculation circuit controlling the image sensor's operation mode based on these data, determining whether the luminance distribution falls within specific thresholds to switch between linear and HDR modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If automatic mode switching is implemented using a soft light-sensitive algorithm relying solely on luminance, then the image sensor can operate automatically without manual intervention, but the scene adaptation capability is poor due to insufficient discrimination between high dynamic range and low dynamic range scenes
Solution Approach 1:
The patent segments the luminance data into statistical characteristics (mean, standard deviation, skewness, kurtosis) to create multiple features for scene analysis. This segmentation of data characteristics enables better discrimination between HDR and LDR scenes, resolving the contradiction by providing more granular information for automatic mode switching while maintaining scene adaptation accuracy.
Solution Approach 2:
The patent implements a feedback mechanism where the control circuit continuously monitors luminance statistical data and adjusts the operation mode based on real-time scene analysis. The system uses the calculated statistical characteristics to feedback into the mode switching decision, improving both automation reliability and scene adaptation by dynamically responding to changing lighting conditions.
2Ease of operation
If manual mode switching is used, then the operation mode can be precisely controlled, but the practicality is reduced due to requiring user intervention in all lighting condition changes
Solution Approach 1:
The patent enables the image sensor system to serve itself by automatically analyzing luminance statistical data and making mode switching decisions without user intervention. The control circuit independently evaluates scene characteristics and selects the appropriate operation mode, eliminating the need for manual control while maintaining precise adaptation to lighting conditions.
3Reliability
If the image sensor operates in high dynamic range mode for all scenes, then overexposure can be prevented in bright scenes, but the efficiency is reduced due to unnecessary complex processing in low dynamic range scenes
Solution Approach 1:
The patent implements dynamic mode switching where the image sensor adapts its operation mode based on real-time luminance statistical analysis. The system transitions between HDR and LDR modes dynamically according to scene characteristics, ensuring overexposure prevention in bright scenes while maintaining processing efficiency in low dynamic range scenes by using the simpler LDR mode when appropriate.
4Device complexity
If the image sensor operates in linear mode for all scenes, then the processing complexity is reduced, but the adaptability is poor due to inability to handle high dynamic range scenes effectively
Solution Approach 1:
The patent creates a universal control system that can handle both HDR and LDR scenes effectively by implementing multi-functionality through statistical luminance analysis. The control circuit universally applies the same statistical analysis framework to determine the appropriate mode, enabling the system to adapt to various scene types (bright, dark, high contrast, low contrast) while maintaining manageable processing complexity through a unified decision-making approach.
Data Source
AI summary
A control circuit and a control method of an image sensor are provided. The image sensor generates a sensed data. The control circuit includes a statistical circuit, an auto exposure (AE) circuit, and a calculation circuit. The statistical circuit generates a luminance statistical data according to the sensed data. The AE circuit sets the image sensor and outputs an AE data which includes a target luminance of the image sensor. The calculation circuit controls an operation mode of the image sensor according to the luminance statistical data and the AE data.