Correct use of color for Cultural Heritage Documentation

Abstract

Accurate color recording is a fundamental feature for proper cultural heritage documentation, cataloging and preservation. However, the methodology used in most cases limits the results since it is based either on perceptual procedures or on the application of digital enhancement techniques only. The objective of this study is to apply a rigorous procedure for the characterization of cameras based on a second-order polynomial model. Trichromatic digital cameras capture color information in the well-known RGB format. Nevertheless, the signal generated by the digital camera is device dependent. By means of the characterization, we establish the relationship between device-dependent RGB values and the tristimulus coordinates defined by the CIE standard colorimetric observer. Once the camera is characterized, users obtain output images in the sRGB space that is independent of the sensor of the camera. We applied the methodology on a set of pictures targeting Levantine rock art motifs in Cova Civil (Castellón, Spain) which is considered part of a UNESCO World Heritage Site. We used raw image files, with different exposure conditions, with raw RGB values captured by the sensor. The outcomes obtained are satisfactory and very promising for proper color documentation in cultural heritage documentation.