Colour Characterisation of Digital Cameras by Analysing the Output Data for Measuring the Spectral Response

The background for this work was the wish of a German photographic magazine to have a method for measuring the colour reproduction quality of digital still picture cameras, as well as their ability to be integrated in a colour management workflow. With scanners, characterisation is less difficult because they always use the same light source, and the colours in the photographic materials that are reproduced have very similar characteristics. In digital photography, the lighting conditions change with each scene, and the colours in a scene can be completely different than the colours inherent in photographic material. Therefore, the best way to characterise a digital still picture camera is to measure its spectral response. It should then be possible to calculate the RGB values by just knowing the spectral illumination of the sensor. That is exactly what the IEC TC100/61966-9 “Colour Measurement and Management in Multimedia Systems and Equipment Part 9: Digital Cameras” working draft proposes. The working draft of this standard was published after we already started our work to find out whether this is a possible way to characterise the colour reproduction of a digital camera or not.