Scanning multispectral IR reflectography SMIRR: an advanced tool for art diagnostics

Area of Science:

• Art Conservation Science
• Optical Imaging Technologies
• Materials Analysis

Background:

• Spectral imaging, particularly near-infrared (NIR) multispectral imaging, is valuable for analyzing ancient paintings due to pigment transparency and reflectance variations.
• Existing multispectral NIR imaging systems for art diagnostics have limitations, indicating a need for technological advancement.

Purpose of the Study:

• To introduce the scanning multispectral IR reflectography (SMIRR) technique and its integrated device for artwork analysis.
• To demonstrate the advantages of SMIRR over conventional wide-band methods for analyzing ancient paintings.

Main Methods:

• Developed a no-contact optical scanner prototype (SMIRR) acquiring 14 spatially registered NIR images (800-2300 nm).
• Data analyzed as a spectral cube, enabling multi-NIR reflectography and pixel-specific NIR spectrometry.
• Applied image enhancement procedures like subtraction, ratio methods, false color, and principal component analysis for data interpretation.

Main Results:

• SMIRR effectively analyzes ancient paintings, revealing hidden features and material differences through interband comparisons.
• The multispectral capability allows selection of optimal NIR bands for enhanced detection.
• Demonstrated applications on Italian masterpieces yielded promising preliminary results.

Conclusions:

• SMIRR is an exceptional tool for non-destructive inspection of painting surfaces, offering high-quality, detailed data.
• Its visual data analysis approach makes it accessible to museum staff.
• The technology shows significant potential for further development in art diagnostics.