Surveillance Camera Panning Correction via Edge Value Alignment
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Solution Overview
Problem
Surveillance cameras experience reduced accuracy in panning and tilting due to backlash and out-of-phase issues in their mechanisms, especially with low-priced motors using open loop control, which affects surveillance performance.
Innovation Solution
A method that corrects panning and tilting by calculating edge values between pixel brightness differences and aligning object vertical or horizontal lines with reference lines, using edge detection and automatic exposure parameters to improve alignment accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If low-priced panning motor or tilting motor configured to perform open loop control is used, then device cost is reduced, but panning and tilting accuracy deteriorates due to backlash and out-of-phase issues
Solution Approach 1:
The patent applies feedback by capturing images at panning-completed and tilting-completed positions, detecting edge values and line positions in these images, and using the detected positions to calculate and apply correction values that compensate for mechanical inaccuracies, thereby improving positioning accuracy without requiring expensive closed-loop control hardware
Solution Approach 2:
The patent replaces mechanical precision requirements with image processing and computational correction. Instead of relying on mechanically precise motors and sensors, the system uses captured images, edge detection algorithms, and mathematical correction values to achieve accurate positioning, substituting mechanical complexity with computational processing
2Measurement precision
If sensor assembly is added to obtain actual pan angle and tilt angle, then measurement capability is improved, but panning and tilting accuracy still deteriorates due to mechanical backlash and out-of-phase issues
Solution Approach 1:
The patent introduces captured images as an intermediary medium between the mechanical positioning system and the control system. Instead of directly trusting sensor readings or motor position commands, the system uses images captured at positioning moments as an intermediary to indirectly measure and correct actual position, bypassing the limitations of direct mechanical measurement
3Reliability
If panning and tilting correction is performed to improve accuracy, then surveillance performance is improved, but device complexity increases due to additional image processing and correction calculations
Solution Approach 1:
The system performs self-correction by using its own captured images to identify positioning errors and automatically calculate correction values. The surveillance camera system serves itself by extracting positioning information from its own output images and applying corrections without requiring external calibration equipment or complex additional hardware
Data Source
AI summary
A method of controlling panning of a surveillance camera configured to perform panning over a set angle during a preset mode includes: obtaining an edge value with respect to each pixel of an object captured image of a panning-completed time, the edge value being a difference between brightness of a left adjacent pixel thereof and brightness of a right adjacent pixel thereof; obtaining an object vertical-line number among vertical pixel lines of the object captured image, the object vertical-line number being a number of a vertical pixel line in which a sum of the edge values is largest; and correcting the panning such that the object vertical-line number coincides with a reference vertical-line number corresponding to the panning over the set angle.