Chromatic Space Correction Circuit; Direct Mapping Circuit - Canon 1130 Service Manual

CHAPTER 4 IMAGE PROCESSING SYSTEM
G. Chromatic Space Correction Circuit
The chromatic space correction circuit is used to improve on the reproduction of color for the
printer unit.
The range of color reproduction for photo and computer-generated images is wider than the
range of color reproduction possible by the printer unit, leading to discrepancies in gradation
between the original and its output image. (The data falling outside the color reproduction range of
the printer unit is not reproduced faithfully.)
To compensate for such discrepancies, the copier is designed to identify the chromatic space
(hue, brightness, and saturation) of the original from the RGB data it reads during pre-scanning,
and converts the result into data that fits the range of color reproduction offered by its printer unit,
thereby enabling faithful reproduction of the original.
c
b
a
Range of color reproduction
for photo images
H. Direct Mapping Circuit
The direct mapping circuit is deigned to improve reproduction of intermediate colors (e.g.,
tone of the skin).
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Chromatic Space on a Copy
(hue, brightness, saturation)
c'
b'
a'
Range of color reproduction of
the printer unit
Figure 4-407
CANON CLC1100/1130/1150/1160/1180 REV.0 MAR. 1999 PRINTED IN JAPAN (IMPRIME AU JAPON)
c
Ideal value
c'
b
Output value
b'
a
Chromatic space of
an original
(hue, brightness, saturation)