Adaptive Defogging System Using Illuminance and Histogram Analysis
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Solution Overview
Problem
Existing CCTV systems lack an automatic and accurate defogging function, leading to deteriorated image quality, especially at night or in low illuminance conditions, as current defogging methods are manually controlled and not adaptive to fog states.
Innovation Solution
A defogging system and method that includes an illuminance sensor, a level determiner, and a defogger, which detect surrounding illuminance and analyze image histograms to adaptively adjust the defogging level, scaling the image based on illuminance and fog state, and apply a gamma curve to improve contrast if necessary.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If manual defogging control is used, then the defogging function can be implemented, but the image quality deteriorates at night or when no fog occurs
Solution Approach 1:
The system changes the defogging processing parameters based on illuminance levels and histogram analysis. The level determiner adjusts the defogging level (first level or second level) according to illuminance, and the gamma applier selectively applies gamma correction based on edge amount, optimizing image quality for different lighting conditions while maintaining defogging effectiveness
Solution Approach 2:
The system uses feedback from the illuminance sensor and histogram analysis to automatically adjust defogging parameters. The edge detector provides feedback on edge amount to determine whether gamma correction should be applied, creating a closed-loop control system that adapts to current imaging conditions and prevents quality deterioration
2Manufacturing precision
If automatic defogging based on illuminance and histogram is implemented, then image quality is maintained, but the device complexity increases
Solution Approach 1:
The image processing apparatus performs multiple functions using a unified processing framework: it conducts histogram analysis, detects edges, determines defogging levels based on illuminance, applies scaling transformation, and selectively applies gamma correction. This multi-functional approach maintains image quality while avoiding the need for separate complex subsystems for each processing task
3Illumination intensity
If gamma correction is applied to all images, then contrast is improved, but processing time increases and may cause unnecessary adjustments
Solution Approach 1:
The system applies gamma correction only partially - specifically when the edge amount is less than or equal to a threshold value indicating foggy conditions. This selective application avoids unnecessary processing of clear images, reducing overall processing time while maintaining contrast improvement where it is actually needed
Data Source
AI summary
Provided are a defogging system and a defogging method. The defogging system includes: an illuminance sensor configured to detect a surrounding illuminance; a level determiner configured to determine a defogging level of the input image based on the detected surrounding illuminance; and a defogger configured to determine a fog state of the input image based on a histogram of the input image, and adaptively defog the input image according to the determined fog state and defogging level.