It’s an enormous privilege talking about my favourite subject to such a group of experts, especially on this hallowed ground, the stage of the Savoy Theatre in London’s Strand – the very first public theatre in Britain to be lit by means of the incandescent electric lamp. This was a real technological and artistic revolution not only of theatre technology but also the development of world theatre itself.
Let me take you back, one hundred and thirty four years to 1881 to tell you about a technology which changed everything. Not just lighting techniques, but scene painting, makeup, costume, acting styles, and playwriting itself.
Original interior of Savoy Theatre, 1881. Credit: Wikimedia Commons.
Welcome to the lighting revolution
In lighting applications, the adoption of light-emitting diodes (LEDs) and organic LEDs promises to reduce lighting energy use dramatically over the next few decades. There is an equally marvellous scientific revolution in biology and psychology. In 2002, we learned conclusively that there is a class of photoreceptive cells in the retina, the intrinsically photoreceptive retinal ganglion cells (ipRGCs), that is separate from the rod and cone cells that transduce visual signals (1). Thus, the eye-brain connection is far more complex than previously thought, and the more we learn the more complex we find it to be (2). Ever since this discovery, debate has raged concerning how to apply this knowledge, and how quickly to do so (3).
One reason for caution is that lighting installations serve many functions, and our recommendations reflect this complexity. As I wrote in a previous blog entry, lighting quality exists at the nexus of the needs of individuals, the environmental and economic context, and architectural considerations. Strong evidence is needed to intelligently blend new discoveries into coherent guidance in balance with the other considerations.
Simplified schematic diagram of two eye-brain pathways, taken from CIE 158:2009. Light received by the eye is converted to neural signals that pass via the optic nerve to these visual and non-visual pathways. POT = Primary optic tract. RHT = Retino-hypothalamic tract. LGN/IGL = Lateral geniculate nucleus / Intergeniculate leaflet. SCN = Suprachiasmatic nucleus of the hypothalamus. PVN = Paraventricular nucleus of the hypothalamus. IMLCC = Intermediolateral cell column of the spinal cord. SCG = Superior cervical ganglion. CRH = Corticotropic releasing hormone. ACTH = adrenocorticotropic hormone. (c) CIE, 2009. Used by permission.
Light is the connection between objects and human beings and it assures visual perception. Changing light the colours and the feeling of paintings change. In these years there is a great revolution in the lighting market, new lighting sources are developed and they allow sophisticated and innovative solutions. The research for LED obtained important and exceptional results offering new technologies able to open new lighting scenes. This new lighting source offers many advantages and also a wide variety of different lighting spectrum not expected in the past years. To find the best light it is important every time but it is fundamental speaking of visual art. Light in fact is able to interfere on conservatory aspects and to change colours and the final visual effect of artworks.
‘Memory of light’ by Giovanna Rasario.
Security in today’s world is defined by light. Yes, that CCTV camera you passed on your way home from work, that License Plate Recognition Camera at the car park, that facial recognition system in the airport or any camera for that matter – they all need light to work well – fact. Without light, there is no image. Without the right/good light, there is no good image. But not all light is the same, and it is the quantity, quality and distribution of light that governs image quality. Light is indispensable to security cameras and good lighting determines whether the captured images will stand up to intense scrutiny and deliver the required results. Sure, all cameras deliver good images during the day – easy. But most crime occurs at night and it is the night time performance of your camera which should most interest you and when good lighting really counts and can make the difference.
It is impossible to separate our vision from light, but the relationship between light, vision and perception is not completely clear nowadays. We can see an object because the light hits the object, the object reflects some wavelengths and part of the electromagnetic radiation can reach our retina, but the result is very complex, and a huge part of the process of vision happens inside our brain. Our retina is something completely different from the CCD of a photographic camera, because in a certain sense the retina is a part of a brain that can pre-process the light signal.
Adelson Checkboard. Credits: Edward H. Adelson