Color Matching Light Cabinets

Color matching light cabinet is a light booth designed to provide a standard set of lighting conditions for visual color inspection. The three most common types of light sources used in the world are incandescent, fluorescent and daylight. In theory, if the product color matches under these light sources in the cabinet, it will match in the real world.

Image: GTI Light Cabinet

Typically:

1. the daylight light source replicates the natural lighting - outdoor lighting
2. the incandescent for the tungsten light bulb and
3. fluorescent for the CFL light bulbs used for lighting up the office, mall and home.

Another light source commonly found in light cabinets is ultraviolet (UV) light. UV is used to observe the presence of fluorescence materials. The next time, when you are in a disco, observe how white fabrics glowed under UV lighting.

Light cabinets are used by manufacturers to ensure that their products matches in these lighting conditions and minimise color differences and metamerism.

The color difference between the zipper and the master color is larger under daylight than under tungsten light. Which means that it would look odd outdoor or in a place lit by fluorescent lighting.

Observe that the zipper has optical brightener agent (OBA) or fluorescence whitening agent (FWA) which causes the zipper to 'glow' under UV lighting whereas the master color has no OBA or FWA and under UV light (which has no color component), the sample looks 'black'.

This is not an optical illusion. It can be scientifically explained.

Welcome to the world of colors.

Oh No!

Anna complained, “I tried out this pair of blouse and skirt at the fashion store and they matched but when I went to Cheryl’s wedding at the beach hotel, they looked awful, the colors do not match”.

Have you got this experience before, you tried out a nice outfit in a mall and when you wear them outdoors, the colors looked ‘off’? This phenomenal is known as Sample Metamerism, where two color samples appear to match under one light source and then do not match under another light source.

Most people experienced sample metamerism when putting on two different outfit where the colors looked similar in the mall where incandescent lights (warm lightings) are used but later found that they don’t match outdoors (which is natural lighting). Or they may not match indoors in the office lit by fluorescent lights.

Color has a spectral reflectance characteristics and lighting has color component and has a power distribution characteristics. By illuminating objects with lights of considerable differing spectral power distributions, metamerism will occur.

Incandescent lighting contains little blue light in shorter (blue) wavelengths and thereby is not able to bring out the blue colors of an object. And at the opposite end, the fluorescent lighting emits more short-wavelength light and this leads to two different visual difference.

On this note, when you are out buying lightings, check out the color temperature of the lights. It gives you an idea of the 'color' of the light.

Don't worry too much about metamerism with high end fashion. Garment manufacturers take lots of effort to use the right dyestuff to avoid this issue. In fact, these controls are done in fashion accessories, cars, white goods manufacturing to make sure you are not embarrased by 'mismatched' shades (the brand too).

Well, no harm trying out your next purchase under different lightings.

Happy shopping.