In Situ Measured Spectral Radiation of Natural Objects

17th Color Imaging Conference Final Program and Proceedings - Dietmar Wüller (Image Engineering)


The only commonly known source for some in situ measured spectral radiances is ISO 17321-1. It describes the principle of how the color characterization of a digital camera works and provides spectral radiances for 14 common objects.

This paper summarizes the results of a project that was started to collect several hundred measurements of all different kinds of objects under various illuminations keeping in mind typical scenes and objects that people take photographs of. In many cases the spectral radiation of objects is not only that of the reflected light.

Sometimes the light coming form objects like leaves for example is a mixture of the reflected and the transmitted light. In other cases inter reflections between the objects modify the spectral radiance in scenes and some objects like the human skin appears totally different in real live compared to the skin tones of a reflective color target.

The collected data can be used as a scientific data basis for different studies related to natural objects. But the main reason to collect the data was to provide training data for the color characterization of digital cameras.

Future work will show whether a carefully collected subset of the database is sufficient to create an ideal matrix or look up table for a digital camera but for the time being all app. 2500 measurements are available and used to calculate camera matrices.

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