Kaveh Ahmadian is currently a Pre Doctorate researcher in the Light and Lighting laboratory in KU LEUVEN university in Belgium. He is a guest lecturer at Iran University of Science and Technology and he has been promoter and co promoter for several research projects. He is also founder and president of Iran Lighting Design Conference (ILDC) which is one of the leading conferences in this field Middle East. Kaveh is founder and CEO of Noorsaform Lighting Engineering which is a lighting solution company located in Iran. He has published several books related to lighting in Farsi and several papers.
Towards Finding the Optimal Illumination Spectrum for a Particular Retail Scene
More than 80% of the data that a human being receives from the surrounding environment comes through the visual system.. Several studies show that light can significantly influence people’s mood, it can affect buyers appreciation of goods and the way a retail store has been lit can transfer a message to visitors about the brand or product.
Finding the optimum spectrum of a light source has since long been an interesting research field, but especially recently, with the advent of LED lighting and its spectral tuning capabilities. In several research projects, the effect of saturation changes due to the illumination on people’s appreciation of objects or perceived atmosphere has been investigated. In those studies, it has been found that color saturation significant impacts visual appreciation. Generally, increases in saturation lead to increased visual appreciation. However, little is known about the tolerances for saturation enhancement, nor on the specifics of the relation between appreciation and the direction and magnitude of saturation changes in various hue regions (cfr. color gamut changes). Also, only a few studies have investigated gender specificity, application dependence and object identity. For example, higher saturation for vegetables and fruits may lead to a less natural appearance or in the case of blue jeans, some studies show that observers prefer less saturated colors. This paper will address lighting color quality from a holistic point of view. Investigation will start from a complex naturalistic scene. With a colorimetric camera, the scene will be recorded and possible high level general scene descriptors such as dominant hue/ensemble hue, overall saturation, contrast and gamut shape will be defined by the use of image processing techniques.
A spectrally tuneable light source with 14 12-bit channels has been developed to be able to generate different spectra. Code has been written to calculate the required gain of the different channels to mimic specific target spectra or to generate spectra with a specified chromaticity and color rendition properties (e.g. CIE Ra, IES Rf and Rg, MCRI Rm, …). Generated spectra are measured with an spectrometer with cooled CCD detector to ensure the accuracy of the spectra after suitable calibration.
Subjective aspects of color quality such as preference, naturalness, vividness and discrimination will be investigated by questioning observers and based on these findings, a relation between scene descriptors and subjective descriptors will be established. This correlation would enable the lighting designer to give some recommendation about the optimum spectrum for a given retail scene.