characteristics of light-sensitive materials,
while
is
the
measuring to determine the needed data.
Figure 2-8.
Sample of a pH scale and readings
(1) Sensitometric quality control. Sensitometric quality control is
a method of analyzing the effects of exposure (light) and processing
(development) on photographic materials.
It will increase the quality of
your photographic products and ensure that you maintain quality production.
(a) For a precise discrimination of the photographic image, we
need something other than verbal characterization of an image.
We need
data: numerical data to describe both the subject and its corresponding
photographic reproduction.
Once we have data, we can sensibly compare
photographic products with original subjects in ways that would be
impossible if we were restricted to personal likes and dislikes.
(b) When we look at a scene, we see differences in shapes, sizes,
and colors that make up that scene. We also see differences in tone, such
as lightness and darkness differences. Most scenes contain many graduated
tones between the darkest and lightest tones.
An average scene has
approximately 160 different tones. The lightest and darkest tones are the
two most important. The ratio of these two values represents the range of
tones or the "scene brightness range" (SBR) of any scene.
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