How important really is the print viewing lighting?

Do I need special lights and can Colourhead supply them?

The short answer is extremely important and yes Colourhead can supply them. I have often been told, “I don’t need any special lighting, none of my clients have it.” I would have to say that this is one of the best reasons to have daylight corrected lighting in-house or what is more accurately referred to as full spectrum lighting. The science behind creating and evaluating true daylight lighting is quite complex and if you think that fitting fluoros purchased at the hardware store with Daylight written on them is anything like corrected lighting then we definitely need to talk.

In my very early days in colour management one of my first wow moments was when I read that, to see a colour that colour must exist in the light source. I had never thought about it but of course when I did give it thought, it was obvious. When we look at an object we only see the reflected colour and light is a combination of all the various wavelengths in the visible spectrum. To see any particular colour that wavelength must exist in the light source and be reflected back to us. If the energy or intensity at any specific wavelength is low for example then what is reflected back to us will be dull. Conversely if a particular wavelength has more energy or intensity than others then that colour will appear brighter. That is why full spectrum lighting is balanced to appear “normal” and just any lighting with daylight stamped on it is about as useful as the proverbial ashtray on a motorcycle.

It is true most printer’s clients won’t have any specialised lighting and it is also true that in many rooms in the clients place of business the print colour will look wrong and if they are unaware of the lighting issues they may and do go back to the printer with a complaint. The printer needs to be able to say that they print to known print standards and have the proper lighting in place to visually assess the work correctly. If necessary they need to be able to back this up with confidence and offer for the client to come down and assess the printing under the correct lighting conditions. This is also a good reason to have full spectrum lighting in the area where clients receive and view their work, in order to avoid this very problem of colour perception when the client returns to their own site, not just at the press console.

I always evaluate the lighting at a site and pay particular attention to the press console area and I have come across some real shockers. It is a funny thing that the cost of the correct lighting is one of the lowest cost items directly related to quality in a print business and yet I can tell you from long experience it is one of the hardest items to sell.

The lights I supply have the highest CRI (Colour Rendering Index) of any I have seen and yet are priced considerably lower than competing products. Basically CRI refers to how well a light compares to a particular phase of daylight referred to as D50. A perfect match would be a CRI of 100 and for critical colour viewing a minimum score of 90 is required. A daylight tube from the hardware store could well be in the 30s. Many people who feel they have some knowledge on the subject will ask for lighting with a colour temperature of 5000k (degrees Kelvin) but this covers only one aspect of the lighting requirement.

I can remember back in the 80s when working in the photographic industry when we all felt very pleased with ourselves for knowing about this colour temperature requirement and not only that, we had the equipment to measure it, a colour temperature meter. We would purchase what was called tri-phosphor fluoro tubes and install them with pride. Unfortunately when affordable spectrophometers became available we discovered to our horror that apart from being 5000k (a bit blue looking compared to other tubes) they were pretty much rubbish. With the introduction of spectrophotometers, lighting was gauged with the very scientific sounding, spectral distribution graphs. Instead of comparing the lights at a single point such as 5000k with a colour temperature meter, lights could be measured and assessed at many points over the entire visible spectrum.