Canon iR2000 Series, Service Manual

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CHAPTER 3 IMAGE READING/PROCESSING SYSTEM
COPYRIGHT© 2002 CANON INC. 2000 CANON iR1600/iR2000/iR1610/iR2010 SERIES REV.0 MAR. 2002
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4.12 Binary Processing
The machine uses an error diffusion method to covert 8-bit (256-gradation) image data
into 1-bit (binary) image data.
4.12.1 Error Diffusion
To convert 8-bit (256-gradation) image data into 1-bit (2-gradation) image data, the ma-
chine tries to find out whether the level of a specific image signal is higher or lower than a
threshold level: 8-bit image data (0 through 255) into 2-bit image data (0, 1). At this time,
the difference of the signal from the threshold level is “diffused” to its adjacent signals
(pixels) to express the gradation (dark, light) of the original image.
4.13 Image Memory Control
The image memory is used as follows:
4.13.1 Compression/Expansion, Rotation, and Enlargement/Reduction
The machine uses image memory to subject binary image signals to compression/ex-
pansion, rotation, and the like.
4.13.2 SDRAM
The machine uses image memory to store image data for image memory functions.
REF.
The machine is designed for memory copying only (no direct copying).
The machine stores the image data once in its memory before generating
output, at times resulting in inadequate available space when continuous
copying is under way with the ADF in use. In such an event, the machine
will stop reading the original, generate copy output, and resume reading
when adequate space has been created.
The machine generates sometimes a memory full error by the memory
space. If the memory full error, divide the original into some stacks and
scan them one by one.