Black Level Correction Circuit Thermal Noise Mitigation
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Solution Overview
Problem
Image sensing apparatuses face issues with thermal noise-induced black level increases and color shifts due to temperature variations, leading to undesired changes in image quality, particularly when capturing images in high-temperature environments.
Innovation Solution
An adaptive black level correction method that generates a black offset for pixels in the active area based on reference black offsets and a ratio determined by current and reference thermal noise information, allowing for the generation of corrected pixel data to mitigate thermal noise effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If the image sensing apparatus operates in high-temperature environments, then the pixel array can capture images continuously, but thermal noise increases causing black level increases and color shifts
Solution Approach 1:
The patent performs preliminary black level calibration at different temperatures before actual image capture. The system pre-determines black level values at multiple temperature points and stores them for later retrieval, so that when thermal noise becomes an issue during operation, the correction data is already available without requiring real-time computation
Solution Approach 2:
The system continuously monitors temperature and adaptively selects appropriate black level calibration values from stored data based on current temperature conditions. This feedback mechanism ensures that the black level correction keeps pace with temperature changes, maintaining image quality during continuous operation in varying thermal environments
2Object-affected harmful factors
If adaptive black level calibration is performed at multiple temperature points, then thermal noise effects are reduced, but system complexity and calibration time increase
Solution Approach 1:
The patent implements black level calibration at a limited number of discrete temperature points (e.g., 5-10 representative temperatures) rather than continuously across the entire temperature range. This partial sampling approach provides sufficient correction capability for most operating conditions while avoiding the excessive complexity of full-range continuous calibration
Solution Approach 2:
The calibration system is designed to serve multiple temperature conditions using a single set of calibration procedures and data structures. The same calibration framework handles all temperature points, and the system universally applies the selected calibration data regardless of which specific temperature condition is encountered, simplifying the overall system architecture
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method effectively reduces thermal noise-induced black level increases and color shifts, ensuring more uniform and accurate image capture by adaptively calibrating black levels across the pixel array, even in varying temperature conditions.
Implementation Method 1
converting light energy into electricity and outputting the electricity to form an image
Implementation Method 2
Thermal energy is the main factor that makes the dark current increase
Data Source
AI summary
An image sensing apparatus, a black level correction method thereof, and a computer readable medium are provided. The image sensing apparatus comprises a pixel array and a black level correction circuit, and the pixel array comprises an optical black area and an active area. The black level correction circuit generates a black offset with respect to a pixel in the active area according to a plurality of reference black offsets with respect to a plurality of reference pixels which are neighboring the pixel and a ratio determined according to a current thermal noise information and a reference thermal noise information. The black level correction circuit generates a corrected pixel data of the pixel according to original pixel data of the pixel and the black offset.