Video Camera Night Mode Switching Using IR Illuminator Dimming
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Solution Overview
Problem
Current methods for switching between night-mode and day-mode in video cameras often result in flickering and wear on actuators due to inadequate assessment of ambient light levels, particularly in low-light conditions, and add complexity with auxiliary light sensors.
Innovation Solution
A method that involves acquiring a stream of images with reduced IR illuminator output to assess ambient light levels, using the image sensor as a light sensor, and adjusting parameters like exposure and gain to seamlessly switch between night-mode and day-mode operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an auxiliary light sensor is used to control switching between night-mode and day-mode, then the assessment of ambient light levels becomes more accurate, but the device complexity and cost increase
Solution Approach 1:
The image sensor is made to serve dual purposes: capturing image data during night-mode operation and functioning as a light sensor for assessing ambient light levels to control mode switching. This eliminates the need for a separate auxiliary light sensor, reducing device complexity and cost while maintaining accurate ambient light assessment capability
Solution Approach 2:
The camera system uses its own image sensor to assess ambient light conditions for mode switching decisions, rather than relying on external or auxiliary components. The system serves its own control needs by processing image data internally to determine when to switch between night-mode and day-mode operation
2Speed
If the switching threshold is set to be responsive to light changes, then the camera adapts quickly to changing light conditions, but flickering occurs due to back-and-forth switching
Solution Approach 1:
The system performs preliminary assessment of ambient light levels by analyzing image data before actually triggering a mode switch. This allows the system to anticipate light level changes and prepare for switching, reducing reactive back-and-forth oscillations and improving switching stability while maintaining responsive adaptation to genuine light condition changes
3Adaptability or versatility
If the IR-cut filter is moved frequently between day-mode and night-mode positions, then the camera adapts to changing light conditions, but wear on the actuator increases
Solution Approach 1:
The system uses preliminary assessment of ambient light conditions through image data analysis to determine when mode switching is truly necessary. By evaluating light levels before switching, the system avoids unnecessary actuator movements, reducing wear on the actuator while maintaining the ability to adapt to genuine changes in lighting conditions
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
Enables a reliable and swift assessment of ambient light levels, minimizing flickering and wear on actuators, while reducing the need for additional components and processing power, ensuring a smooth transition between modes.
Implementation Method 1
the incident light detected as a charge on individual photodetectors
Implementation Method 2
an IR illuminator... with the IR illuminator having a first illumination output level
Data Source
AI summary
A method for assessing an ambient light level during video acquisition with a video camera is provided. The video camera is operably connected with an IR illuminator, and having a day mode in which an IR-cut filter is arranged in front of an image sensor and a night mode in which the IR-cut filter is not arranged in front of the image sensor. The method comprises:acquiring a stream of images with the video camera in night mode, with the IR illuminator having a first illumination output level, and thenreducing an output level of the IR illuminator to a predetermined illumination output level during acquisition of a sequence of a predetermined number of consecutive image frames within the image stream, and thenassessing a measure representative of an ambient light level from an evaluation of the sequence of image frames.