Early Cinema: spectral and colorimetric analysis of Tinting dyes for film restoration

Early cinema is often mistakenly imagined as completely silent and colorless. However, in reality, movies were not only accompanied by live music and live dialogue but also had the presence of color. One of the Early Cinema's main coloring techniques was tinting, which allowed the coloring of entire frame sequences with dyes. The colors used in tinting had nothing to do with the natural colors of reality, as producers focused solely on their visual effect and the meaning conveyed in the scene's narrative. Therefore, restoring films from this period is extremely difficult because, when the film fades or deteriorates over time, it is almost impossible to restore the exact colors without reliable information or references from the originals.In this work, we perform a spectral and colorimetric study of the Tinting dyes used in Early Cinema, starting from the literature. The aim is to establish a scientific base that can aid and support the cinematographic restoration of these films during digital color reproduction. First, we conducted historical and bibliographical research on the early 1900s cinematographic dyes. We traced the dyes and their official production methods for tinting through the various editions of Eastman Kodak's Tinting and Toning of Eastman Positive Films book from 1918 to 1927. We then searched for the UV-Vis spectra of these compounds, from which we computed a colorimetric analysis. The RGB values of each dye allowed us to create a colormap to digitally recreate the effect of tinting on a black-and-white image.This preliminary study shows that spectral and colorimetric data could be useful to digitally recreate the colors of the Early Cinema faithfully to the original colorants. Further investigations must increase the number of dyes and deepen the spectroscopic research, as the spectra of the chemical compounds used in this study do not necessarily correspond to the concentrations specified in the original coloring preparation recipes.