We need three conditions for color to exist.
Light must exist for the object to reflect it and for the observer to see
it.
Objects have physical properties that cause them to absorb or reflect various
parts of the visible light spectrum.
Color is a psychophysical phenomenon. Color only exists in the
observer's conscious mind.
Without any one of these three elements, color cannot exist.
Because the observer's perception of color occurs in the brain, it can be affected by changes in body chemistry. This means if you are sick, tired, consumed alcohol,or any number of other factors, you will perceive color differently than you normally would.
It is important to understand the color temperature of light with regards to judging image color on monitors and in ink-jet prints.
Light is measured in the kelvin temperature scale, named for Lord Kelvin (William Thomson.)The kelvin scale measures absolute temperature. The importance of the kelvin scale to digital printers is in viewing images on monitors and viewing prints under controlled lighting conditions. Most people use a standard of 6500k (D65 illuminant) to calibrate their monitors. This may seem contrary to the recommended print evaluation viewing temperature of 5000 to 5500k. Some experts recommend calibrating monitors to 5000k since this is the standard viewing booth color temperature. Some color management systems allow you to make a profile for a specific lighting situation. Don't get too wrapped up in theses variables. As long as you are using one of these kelvin standards, you will achieve very acceptable results.
It is important to view your images on the monitor in a room with low level lighting. The recommended level is 35 lux, but not more than 50 lux. It is also important to view your images in a D50 illuminant view situation. Watch out for brightly colored walls that may surround your viewing situation. If you are doing color-critical work with clients who are distant from you, make sure they have the same exact viewing conditions as yours. If you will be displaying work in a gallery or other special lighting situation, find out what type of lighting they have and, if possible, recreate it in your viewing situation. If you want to be really compulsive about judging output color, wear neutral color clothing!
