Video Camera Exposure Adjustment Using Weighted Image Segmentation

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Solution Overview

Problem

Video cameras in security systems often lose detail in darker areas due to exposure settings being skewed by bright areas, which are not typically of interest, leading to important objects being obscured in images.

Innovation Solution

The method involves segmenting captured images into window segments, identifying and excluding bright areas that cover less than a certain percentage from exposure settings calculations, and adjusting camera control parameters based on calculated exposure settings to enhance darker areas.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If exposure settings are calculated based on average metering of the entire scene, then the exposure settings reflect the overall scene brightness, but bright areas skew the exposure settings and cause loss of detail in darker areas

Engineering Contradiction:

Improveexposure settings calculation accuracyVSAvoiddetail loss in darker areas

Core Design Contradiction:

Measurement precisionVSLoss of information

Solution Approach 1:

The image is divided into multiple regions (center region and surrounding regions) with different weighting factors. The center region has a higher weighting factor (e.g., 9) while surrounding regions have lower weighting factors (e.g., 1), allowing the exposure calculation to focus more on the important central area while still considering the overall scene.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the image are assigned different importance weights based on their location. The center region, where important objects are typically located, is given higher weight to preserve detail, while peripheral bright areas are given lower weight to prevent them from skewing the exposure settings.

Inventive Principle:

Principle #3Local quality

2Measurement precision

If exposure settings are calculated using spot metering on a small focus area, then the exposure settings accurately represent the focus area, but light from other areas is not factored into the exposure settings

Engineering Contradiction:

Improveexposure settings for focus areaVSAvoidexposure adaptation to overall scene

Core Design Contradiction:

Measurement precisionVSAdaptability or versatility

Solution Approach 1:

The image is segmented into a center focus area and surrounding areas, with the center area receiving higher weighting for exposure calculation. This maintains the focus-area precision of spot metering while incorporating information from surrounding regions through lower weighting factors.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The weighting factors are dynamically adjusted based on the scene content and lighting conditions. The system can adapt the relative weights of different regions to optimize exposure for the specific situation, combining the benefits of spot and average metering.

Inventive Principle:

Principle #15Dynamics

3Measurement precision

If exposure settings are calculated using center-weighted metering, then the center area is weighted more significantly, but bright areas in the center can still skew the exposure settings

Engineering Contradiction:

Improveexposure settings for center areaVSAvoiddetail loss when center has bright areas

Core Design Contradiction:

Measurement precisionVSLoss of information

Solution Approach 1:

The system applies partial weighting to the center region rather than full weighting. By using a weighting factor that is high but not maximum (e.g., 9 compared to 1 for surrounding areas), the center area influences the exposure settings significantly but not excessively, preventing bright center areas from completely dominating the calculation.

Inventive Principle:

Principle #16Partial or excessive action

Solution Approach 2:

The weighting factors are adjustable parameters that can be modified based on scene analysis. When bright areas are detected in the center, the system can dynamically adjust the weighting factors to reduce their influence, preventing skewing while maintaining center-area focus.

Inventive Principle:

Principle #35Parameter changes

4Adaptability or versatility

If multi-zone metering is used to use light from multiple areas, then the exposure settings consider more of the scene, but bright areas in any zone can still affect the exposure settings

Engineering Contradiction:

Improveexposure consideration of multiple areasVSAvoiddetail loss due to bright area influence

Core Design Contradiction:

Adaptability or versatilityVSLoss of information

Solution Approach 1:

The scene is divided into multiple zones with hierarchical weighting, where the center zone has the highest weight and peripheral zones have progressively lower weights. This segmentation allows multi-zone metering to consider the entire scene while preventing peripheral bright areas from having excessive influence on the final exposure settings.

Inventive Principle:

Principle #1Segmentation

Data Source

PatentUS9313415B2Method and system for adjusting exposure settings of video cameras

Publication Date: 2016.04.12 TYCO FIRE & SECURITY GMBH

AI summary

A system and method to enhance dark areas of a scenes while preventing bright areas of the scenes from distorting or skewing exposure settings of video cameras. The video cameras capture images and identify bright areas in the captured images. The video cameras calculate exposure settings while excluding the bright areas in the captured images to enhance the dark areas in the captured images. Camera control parameters are then adjusted based on the calculated exposure settings.