Polytechnic University of Valencia Congress, 1st Congress in Geomatics Engineering

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SOFTWARE DEVELOPMENT FOR COLOURIMETRIC AND SPECTRAL DATA PROCESSING: PYCOLOURIMETRY
Adolfo Molada Tebar, José Luis Lerma, Ángel Marqués-Mateu

Last modified: 18-10-2017

Abstract


Archaeological documentation is a complex process where the technical measurement and specification of colour is a key aspect. In the last years heritage documentation processes have largely benefited from the application of digital recording methods, imagery analysis software and technologies that offers great advantages over the traditional methods. The rigorous processing of colourimetric data requires software packages with specific colourimetric technical characteristics. In this paper we report on our in-house pyColourimetry software that was developed and tested taking into account the recommendations of the Commission Internationale de l'Éclairage (CIE). The objective is to apply a rigorous procedure for the characterisation of cameras based a priori on polynomial models. Most of the digital cameras capture colour information in the well-known RGB format, but the signals generated by the digital camera are device dependent. By means of the characterisation we establish the relationship between device dependent RGB values and the tristimulus coordinates defined by the CIE standard colourimetric observer. Once the camera is characterised, users have the potential to obtain output images in the sRGB space that is independent of the sensor of the camera. pyColourimetry software allows users to control the entire digital image processing and the colourimetric data workflow proposed. We applied the methodology on a set of pictures targeting Levantine rock art motifs in Cova dels Cavalls (Castellón, Spain) which is considered part of a UNESCO World Heritage Site. The outcomes obtained are satisfactory and very promising for proper colour documentation in cultural heritage estudies.

http://dx.doi.org/10.4995/CIGeo2017.2017.6568


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