Shadow Segmentation With Image Thresholding for Describing the Harshness of Light Sources

Area of Science:

• Optics and Photonics
• Image Analysis
• Lighting Technology

Background:

• Traditional light source characterization (luminous intensity, color temperature, color rendering index) often omits light quality metrics like harshness or softness.
• Light source harshness, related to shadow characteristics, is a critical but often overlooked aspect of illumination.
• Existing shadow detection methods in image analysis primarily focus on shadow removal, not quality assessment.

Purpose of the Study:

• To develop and validate a novel method for quantifying the harshness or softness of light sources.
• To establish a standardized numerical evaluation for light quality based on shadow analysis.
• To assess the effectiveness of the method across different light sources and light-shaping attachments.

Main Methods:

• Image analysis techniques to isolate shadows from test images.
• Thresholding for segmenting shadows into umbral and penumbral regions.
• Calculation of a shadow metric and a final numerical evaluation of light source quality.

Main Results:

• The proposed method successfully quantifies light source harshness, providing a single, objective metric.
• The technique is independent of light source intensity, focusing solely on light quality.
• Effective analysis of halogen, LED, and xenon light sources, including those with light-shaping attachments.

Conclusions:

• A new, efficient method for evaluating light source harshness based on shadow analysis has been developed.
• The method offers a potential standardized approach to describing light quality and the performance of light-shaping devices.
• This quantitative measure of light softness/harshness addresses a gap in current light source characterization.