Calculation of Non-Visual Effect of Lighting Environments Based on Spectra Information Recovered from High Dynamic Range Images

Since lighting is an important factor affecting the office comfort and circadian rhythm of workers inside, how to easily and effectively quantify the lighting index is important. The traditional quantification method relies on the use of many equipments, such as luminance meters, illuminance meters and spectrum measurement devices, etc. This paper proposes a comprehensive method to use high dynamic range images for the measurement tasks. Especially for the non-visual effect of lighting, which is highly relied on the spectrum, the RGB information of a high dynamic range image is read and combined with a pre-calculated spectral baseline to generate a relative spectrum. Later, the relative spectrum is calibrated to obtain the absolute spectrum. The equivalent melanopic lux and circadian stimulation index was calculated based on the recovered spectra and compared with the one derived from the measured spectrum measured using CL-500A. The experiments were performed in multiple indoor rooms and the results show that the errors are all within 10%. The HDR based method has the advantages of low cost and easy operation compared with the traditional method, which can be seen as a new scheme for the quick acquisition of non-visual effects of a lighting environment in the future.