Spatial-Spectral Evidence of Glare Influence on Hyperspectral Acquisitions

Area of Science:

• Optics and Photonics
• Image Analysis
• Spectroscopy

Background:

• Glare is a common issue in optical imaging systems.
• Hyperspectral imaging (HSI) is sensitive to optical phenomena.
• Quantifying glare's impact on HSI data is crucial for accurate analysis.

Purpose of the Study:

• To present the first set of hyperspectral image acquisitions and measurements to verify glare's effect on HSI data.
• To introduce a new metric, the Glare Effect (GE) index, for quantifying glare.
• To evaluate glare's influence in both spatial and spectral domains under various conditions.

Main Methods:

• Acquired hyperspectral images of ColorCheckers (CCs) under varied lighting, backgrounds, exposure times, and orientations.
• Compared reflectance spectra from HSI with reference measures from contact spectrophotometers.
• Developed and applied the Glare Effect (GE) index by comparing CC grayscale patch contrast in HSI versus reference spectra.

Main Results:

• Glare was quantified across all HSI acquisitions, revealing an unwanted light contribution.
• The Glare Effect (GE) index successfully identified and measured glare's influence.
• Glare's impact was found to increase for darker pixels and those adjacent to light sources or bright patches.

Conclusions:

• Glare significantly affects hyperspectral image data quality.
• The developed Glare Effect (GE) index provides a reliable method for assessing glare in HSI.
• Understanding and mitigating glare is essential for accurate spectral reflectance measurements in HSI applications.