Minolta Di450 Service Manual page 42

The threshold value is transmitted from the IRC to the IR Density Correction block.
This block then corrects the image density of incoming data in accordance with the
relation shown below.
Output
X
0
-b
4002M517AA
For all quality modes other than "Photo," the gradation curve of the density-cor-
rected data is adjusted in accordance with the Image Quality mode so as to
enhance the reproduction of the high-density areas.
If the Image Quality mode is set to "Photo," however, the gradation curve is
designed to promote image smoothness, even density, and low noise. In this case,
the curve is adjusted in accordance with the manual density setting, as illustrated
below.
Output
X
Dark
Light
0
4002M519CA
The above processing enables the user to select copy density effectively for any of
the image quality modes.
Before page
X=aχ-b
X: Image density value after density correction
a: 1
χ: Image density value before density correction
-b: Threshold (intercept)
Input
x
Input
x
M-22