IMAGE PROCESSING
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A229 SM
2.3.11 GAMMA (
γ
γγ
γ
) CORRECTION
Gamma correction ensures accurate generation of the various shades in the gray
scale from black to white, accounting for the characteristics of the scanner and
printer.
Scanner gamma correction corrects the data output to the IPU to account for the
characteristics of the scanner (e.g., CCD response, scanner optics).
Printer gamma correction corrects the data output from the IPU to the laser diode
to account for the characteristics of the printer (e.g., the characteristics of the drum,
laser diode, and lenses).
The data for the scanner and printer gamma correction are fixed and stored in the
memory. There are no SP adjustments in this machine.
2.3.12 GRADATION PROCESSING
There are two basic types of gradation processing
•
Printing multi-bit per pixel data as it is (i.e., keeping many image density levels
available for each pixel; in this machine)
•
Reducing the number of possible output levels per pixel, by using only a few of
the range of possible output levels
Various processes are available to try to reproduce various types of original as
faithfully as possible.
In this model, these are three processes:
1. Grayscale processing
2. Error diffusion
3. Dithering
These three processes are used as follows (default setting).
Text mode Grayscale processing
Text/photo mode: Error diffusion
Photo mode: Error diffusion or dithering
Generation Copy Mode: Grayscale processing + line width correction
Pale mode: Grayscale processing
The above information is expressed in the diagram in the Image Processing Path
section.
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