Image analysis pipeline for characterizing photolytic degradation in daguerreotypes

Abstract

We describe an image analysis pipeline for the minimally invasive analysis and characterization of light-induced degradation in daguerreotypes. To our knowledge, this is the first time that quantitative characterization and temporal analysis of the photolytic degradation has been described for daguerreotypes. We measure the impact of degradation using microscopic image capture before and after exposure of a small sacrificial region of the daguerreotype to light. The image analysis pipeline compensates for changes in capture position between the pre and post-exposure images and measures the effects of the degradation in the regions under test. Our results show that photolytic degradation follows a profile that is approximated as the sum of two exponentials with a time constants about 0.41 and 0.003 min-1, with variation across regions.