Video Image Processing Using Sinusoidal Light Modulation
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Solution Overview
Problem
Existing video analysis algorithms face challenges in compensating for varying background lights, which affect color constancy and shadow removal, especially in dynamic and complex lighting conditions, leading to suboptimal performance in object tracking and face detection.
Innovation Solution
A method using a non-synchronized sinusoidally modulated light source, independent of the camera, to capture multiple frames and apply a software filter to separate the background illumination, resulting in images that are independent of lighting conditions, enhancing shadow removal and color correction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If passive color correction algorithms are used to compensate for background lights, then color constancy can be improved under controlled conditions, but performance deteriorates when background lights vary in space, time, and spectra
Solution Approach 1:
The patent applies periodic action by modulating the illumination source sinusoidally at a specific frequency. This periodic modulation allows the system to distinguish between the modulated light and unmodulated background lights through frequency-based separation, enabling accurate color measurement regardless of background lighting conditions. The periodic nature of the modulation creates a consistent signal that can be easily filtered and processed.
Solution Approach 2:
The patent replaces traditional passive optical filters or mechanical light blocking mechanisms with a software-based signal processing approach. By using digital signal processing to analyze the frequency components of captured images, the system can separate modulated light from background lights without requiring physical filtering mechanisms, thereby improving adaptability to various lighting conditions.
2Measurement precision
If active solutions with controlled light sources are used to clear background light effects, then image quality improves, but device complexity and synchronization requirements increase
Solution Approach 1:
The patent replaces complex hardware synchronization mechanisms with software-based frequency analysis. Instead of requiring precise temporal coordination between light source activation and camera capture, the system uses frequency domain separation to identify and extract the modulated light signal from the captured image data, significantly reducing hardware complexity.
Solution Approach 2:
The patent introduces frequency domain analysis as an intermediary between the light source and the final image processing. The sinusoidal modulation frequency serves as a mediator that allows the system to separate the controlled light source signal from background illumination without direct temporal synchronization, simplifying the overall system architecture.
3Measurement precision
If multiple light sources with different modulation patterns are used to distinguish their contributions, then light source separation improves, but processing complexity increases
Solution Approach 1:
The patent applies segmentation by assigning unique modulation frequencies to different light sources. This frequency-based segmentation allows the signal processing algorithm to separate and analyze the contribution of each light source independently through Fourier analysis or similar frequency domain techniques, making it easier to identify and process individual light source effects.
Solution Approach 2:
The patent changes the frequency parameter of the sinusoidal modulation for different light sources to enable differentiation. By varying this key parameter (frequency) while keeping the modulation type consistent, the system achieves light source separation through simple frequency-based identification rather than requiring complex spatial or temporal coding schemes.
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
The method effectively removes shadows and corrects colors, improving image quality by isolating the modulated light source's influence, leading to enhanced contrast and performance in object recognition and detection systems.
Implementation Method 1
the illumination is comprised of unknown background illumination and sinusoidally modulated illumination that oscillates at a unique frequency
Implementation Method 2
capturing with the camera sensor a plurality of N consecutive frames in time containing images of the scene
Data Source
Figure 1a~2b
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Figure 5
AI summary
Methods of creating frames captured with a video camera that are independent of light conditions are presented. In a first method the invention attains this goal by the addition of a modulated light source, for example amplitude modulation (AM), to the background light that illuminates the scene being captured and executing an algorithm that generates processed images in which the effects of the background illumination have been eliminated. In a second aspect the invention is a method of modifying the flash no flash technique by executing an algorithm that averages out the maximum and minimum intensity peaks in adjacent frames thereby allowing this technique to be employed using non- synchronous light in video.