Input Image Processing; Image Data From The Reader Unit; Enlargement/Reduction (Main Scanning Direction); Edge Emphasis - Canon iR105 Service Manual

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2.2 Input Image Processing

Input image data from the reader unit is processed as follows:

The image signals from the reader unit is subjected to shading correction and turned into

8-bit, 256-gradation intensity signals.

The input is from 2 signal lines: even-bit pixels and odd-bit pixels.

Image data is processed when it is written into or read from image memory for enlarge-

ment or reduction.

Edge emphasis is performed so that the text, text/photo, print photo, or print photo images

may be made sharp so as to reduce moiré.

Edit processing is performed to enable the following: blanking/framing, negative/positive

reversal, slant, mirror, fold, repeat.

In this block, intensity signals are converted into density signals; in addition, processing

is also performed so that the output density curve best suited to each mode is obtained.

a. LOG Conversion

Using a LOG conversion table, the intensity signals are converted into toner density sig-

nals in relation to reflected light.

b. Density Adjustment (F-value conversion)

Using an F-value table selected in relation to the setting of the Density key in the control

panel, density adjustment is performed. It, however, will not be performed in memory copy

c. Density Conversion (γ conversion)

Using a γ conversion table, density correction is performed for text, text/photo, print

photo, or film photo mode.

The error diffusion method (TBIC) is used to control the texture, subjecting data to binary

processing so that it becomes most suited for printing. Specifically, the 8-bit image density

signals of text, text photo, or print photo mode are converted into 1-bit image density sig-

nals (binary).

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CANON iR105 REV.0 JULY 2001

CHAPTER 3 MAIN CONTROLLER

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