Night Scene Detection Using Histogram and Point Light Source Analysis
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Solution Overview
Problem
Existing methods for determining night scenes in video processing, such as those based on histogram shape, often inaccurately identify backlit scenes or high-contrast objects as night scenes, leading to incorrect exposure settings and unnatural images.
Innovation Solution
A video processing apparatus and method that utilize both histogram shape analysis and point light source detection, incorporating evaluation values from high-frequency components and pixel ratios, to accurately determine night scenes by meeting specific conditions related to luminance levels and point light source presence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If histogram shape analysis is used to determine night scenes, then the determination process is simple, but the accuracy is reduced leading to erroneous detection of backlit scenes or high-contrast objects as night scenes
Solution Approach 1:
The patent combines histogram shape analysis with point light source detection based on high-frequency components. The night scene determination unit integrates results from both the first determination unit (histogram analysis) and the second determination unit (point light source detection), requiring both conditions to be satisfied. This merging of multiple detection methods resolves the contradiction by maintaining simple individual processes while achieving high accuracy through their combination.
2Productivity
If only histogram shape is used for night scene determination, then the processing is fast, but reliability is reduced due to false positives in backlit or high-contrast scenes
Solution Approach 1:
The system implements a feedback mechanism where the night scene determination unit receives inputs from both histogram analysis and point light source detection, and only determines a night scene when both conditions are satisfied. This feedback-based dual-condition approach ensures reliable determination by cross-validating results, preventing false positives in backlit or high-contrast scenes while maintaining efficient processing through parallel evaluation of both criteria.
3Measurement precision
If histogram thresholds are set to detect night scenes, then some night scenes are detected, but false detections occur in non-night scenes with similar histogram distributions
Solution Approach 1:
The patent introduces point light source detection based on high-frequency components as an intermediary condition. The night scene determination unit uses this intermediary detection method to verify histogram-based determinations. By requiring both histogram shape analysis and point light source detection to confirm a night scene, the system eliminates false detections in non-night scenes while maintaining sensitivity to actual night scenes.
Data Source
AI summary
An imaging apparatus includes a histogram shape determination unit that acquires a histogram of luminance values from video captured by an image capturing unit and determines whether or not the captured video is a night scene from the shape of the histogram. The imaging apparatus also includes a point light source determination unit that acquires the maximum value of contrast for each horizontal line in the video as a line evaluation value and determines whether the captured video is a night scene based on whether or not the line evaluation value has a characteristic of an object as a point light source. If the histogram shape determination unit and the point light source determination unit determine that the captured video is a night scene, the imaging apparatus determines that the scene captured by the image capturing unit is a night scene.