b. Dye Image. The final location of the dye image in the emulsion is
determined by the location of the developed silver grains.
The dyes are
formed in the areas adjacent to the reduced silver.
When the silver is
removed during processing, the dye remains as a cloud centered where the
grain was located. Because the dye images are partially transparent, rather
than opaque, and are formed by chemical diffusion, their density increases
gradually from the edge to the center. On the other hand, the density of a
silver image changes abruptly at the edge of the grain.
Therefore, color
film appears less grainy than black and white, but the image has lower edge
sharpness and image definition.
The magenta dye image (green-sensitive
layer) has the greatest appearance of graininess because the peak
sensitivity of the human eye is in the region of the spectrum.
(1) Atypical emulsion of
color film. Since red, green, and blue are
recorded in the same manner
in almost all color films, negative and
reversal, a cross-section of a
typical emulsion of color film will help in
better understanding. Refer to
figure 1-11.
Figure 1-11.
Color film emulsions
(a) Starting at the top is the blue-sensitive layer of the
emulsion.
This is where the blue record is made.
The blue-sensitive
emulsion is sensitive to blue light only.
(b) Below the blue-sensitive emulsion is a layer
of yellow
colloidal silver suspended in clear gelatin that absorbs the
stray blue
light that penetrates the blue-sensitive emulsion; this layer is
similar in
action to a yellow filter. The colloidal silver is bleached and
fixed away
during the processing.
1-21
SS0514
Previous Page
