Visual tasks include the visual assessment of brightness, visual search, object detection, and visual acuity (object recognition). Visual acuity is the spatial resolving capacity of the visual system, it indicates the angular size of the smallest detail that can be resolved. Visual acuity may be thought of as the ability of the eye to distinguish fine detail. Lighting has a direct impact on visual acuity. Visual acuity corresponds to the ability to recognize fine object details with high luminance and spectral contrast. Objects with high luminance against their background can be easily detected. Light with high color rendering ability improves color contrast and make small objects easier to distinguish from their background. White light with a high percentage of blue light stimulates the ipRGC (intrinsically photosensitive retinal ganglion cell) photoreceptors. Stimulation of the ipRGC photoreceptors cause the pupils to contract, which results in better visual acuity.
