Metering Compensation for Monitoring Camera Visibility

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Solution Overview

Problem

Conventional image exposure adjustment methods fail to maintain visibility across all regions of an image, leading to over-exposure or under-exposure issues, particularly affecting monitoring cameras' ability to clearly capture facial features of individuals in surveillance areas.

Innovation Solution

A metering compensation method that generates a weighted histogram using a convergent target value and minimal mapping value to compute exposure compensation values, adjusting the exposure parameters of a monitoring camera to prevent over-exposure and preserve image details.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If the conventional image exposure adjusting method shifts the whole histogram toward the high-grey-level place to increase intensity, then the intensity of the image is improved, but the visibility of normal intensity distribution regions is spoiled and large blurred regions are created

Engineering Contradiction:

Improveimage intensityVSAvoidvisibility of normal intensity regions

Core Design Contradiction:

Illumination intensityVSManufacturing precision

Solution Approach 1:

The patent divides the histogram into multiple regions (dark region, normal intensity region, bright region) and applies different adjustment strategies to each region. The weighting function assigns different weights to different histogram regions, allowing independent optimization of each region's visibility without affecting others, thus resolving the contradiction between overall intensity improvement and local visibility preservation

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent applies local quality adjustment by using a weighting function that assigns different importance weights to different histogram regions. The weighting function ensures that normal intensity regions maintain their visibility characteristics while still benefiting from overall exposure adjustment, preventing the creation of blurred regions in these areas

Inventive Principle:

Principle #3Local quality

2Illumination intensity

If the conventional image exposure adjusting method adjusts exposure parameter to overcome over-bright or over-dark problems, then the extreme regions are improved, but normal intensity distribution regions are affected and result in low visibility

Engineering Contradiction:

Improveextreme region intensityVSAvoidvisibility information of normal intensity regions

Core Design Contradiction:

Illumination intensityVSLoss of information

Solution Approach 1:

The patent segments the histogram into dark, normal intensity, and bright regions, applying different adjustment strategies to each. The weighting function ensures that extreme regions receive adjustment attention while normal intensity regions maintain their visibility, preventing information loss in these critical areas

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent uses the weighting function as a feedback mechanism that continuously monitors the histogram distribution and adjusts exposure parameters accordingly. The weighting function provides feedback on which regions need adjustment and by how much, preventing over-adjustment of normal intensity regions while correcting extreme regions

Inventive Principle:

Principle #23Feedback

3Illumination intensity

If the monitoring camera uses conventional exposure adjustment, then the overall image exposure is improved, but facial features of unauthorized persons inside monitoring area cannot be displayed clearly

Engineering Contradiction:

Improveoverall image exposureVSAvoid清晰度 of facial features

Core Design Contradiction:

Illumination intensityVSMeasurement precision

Solution Approach 1:

The patent applies local quality adjustment by using a weighting function that assigns different importance weights to different histogram regions. The weighting function ensures that regions containing facial features (typically normal intensity regions) maintain their visibility and detail, while still allowing overall exposure adjustment to improve the appearance of extreme regions

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent segments the histogram to identify and protect regions containing important information such as facial features. By separating these regions from extreme brightness regions, the system can adjust exposure without blurring or losing detail in the facial feature regions, thus improving measurement precision for identification purposes

Inventive Principle:

Principle #1Segmentation

Data Source

PatentUS10904447B2Metering compensation method and related monitoring camera apparatus

Publication Date: 2021.01.26 VIVOTEK INC

AI summary

A metering compensation method for effectively increasing visibility of an image is applied to a monitoring camera apparatus. The metering compensation method includes acquiring a histogram of the image, setting a convergent target value and a minimal mapping value, utilizing the convergent target value and the minimal mapping value to set a weighting function, transforming the histogram into a weighted histogram via the weighting function for acquiring an intensity mean of the weighted histogram, and utilizing the convergent target value and the intensity mean to generate a first exposure compensation value. The first exposure compensation value can be used for determining whether to adjust an exposure parameter of the monitoring camera apparatus.