> <http://www.google.com/search?q=lux+meter+camera> (and Google will be > your friend ;-) > e.g. <http://www.clarkvision.com/imagedetail/digital.photons.and.qe/> > I'd prefer to use a gray card (18% reflectance) instead of white paper. > Klaus Thanks Klaus! I've just spot your message, this article seems to be exactly what I was looking for. Once finish my job, going to place few experiments with estimating ambient light by camera and with help of huey, and see light compensation would affect my current calibration profiles.