Figure 12-4.Ring around.
±590 lux (130 footcandles ±55 footcandles). The color
temperature of the light source should be between
3800 K and 5000 K. The most important characteristic
of the light source is the color rendering index (CRI).
The CRI is a scale from 0 to 100 and is used to describe
the visual effect of a light source on eight standard pastel
colors. For good color rendering in the prints being
viewed, the CRI of the light source should be between
85 and 100.
Fluorescent tubes, such as the Westinghouse Living
White or the Deluxe Cool White tubes (made by several
manufacturers), have at least a CRI of 85 and a color
temperature near 4000 K. Satisfactory results also can
be obtained by using a mixture of incandescent and
fluorescent light. For each pair of 40-watt Deluxe Cool
White fluorescent tubes, a 75-watt frosted tungsten bulb
should be used.
Comparing the test print to a series of prints that
vary from a standard print (correct density and color
balance) in known amounts is a simple method of
determining color and density correction (fig. 12-4).
Comparing your test print to a ring around is particularly