How to Look at Spectral Images? A Tentative Use of Metameric Black for Spectral Image Visualisation

The number of bands of a spectral image makes its visualisation as a traditional colour image a challenge. Several directions are investigated in the literature. The state-of-the-art solutions are all limited, either due to the reduced quantity of information displayed, or to such a severe reduction in naturalness or image quality that it is hard to analyse visually. This article surveys the different attempts and investigates a direction that uses a pair of images rather than a single image. We use the principle of metameric black to provide a dual image for visualisation. One image is then a colorimetric image that encompasses the fundamental metamer information, the other one is based on the metameric black and contains extra information related to the spectral nature of the signal. We show that in the case of metameric samples, this visualisation is useful to provide additional information.