Colorimetric accuracy of high dynamic range images for lighting research

Cauwerts, Coralie [UCL] Jost, Sophie [ENTPE] Deroisy, Bertrand [CSTC/BBRI/WTCB]

High Dynamic Range (HDR) imaging techniques are frequently used in lighting research for measuring luminance. The main objective of this work was to determine to what extent they can also be used for measuring colours. Three professional digital single-lens reflex cameras fitted with fisheye lenses were used for taking HDR pictures. The scene, containing a Macbeth chart and additional Munsell samples, was lit by a LED equi-energy spectrum source. The set of colour samples had first been characterized using a spectrophotometer. This article presents and compares two calibration methods, a conventional and an alternative one. It was demonstrated that the second method is necessary to achieve an acceptable colorimetric accuracy for lighting design of interior environments, and that it improves the luminance accuracy. The study also shows that one of the studied devices has higher accuracy performances.