8. Size/Skew Detection
Size Detection: This is explained in the Scanner Process section.
Skew Detection (ADF mode only): The machine notes the pixel location
across the main scan that data first appears. The machine determines
whether the original is skewed by looking at the data either side of this point
on subsequent main scans. The original width is taken to be the distance
between the vertical scale and that point, so if the original is skewed, this is
not the same as the actual original width, and the CPU discards data from
outside this assumed original width.
9. Zooming Processing
Reduction and enlargement in the sub scan direction are done by changing
the scanner speed. However, reduction and enlargement in the main scan
direction are done by the software.
10. Mirror Processing
A mirror image of the original must be made for output.
11. Dithering
Dither processing produces good quality grayscale images of photo originals.
12. Error Diffusion
The error diffusion process reduces the difference in contrast between light
and dark areas of a halftone image. Each pixel is corrected using the
difference between it and the surrounding pixels. The corrected pixels are
then compared with a matrix table.
After video processing, the data goes to the host computer through the
DRAM and SCSI controllers.
Skewed Original
Actual Original Width
Assumed Original Width
Data to the left of
this line is dis-
carded.
g404d514.wmf
Det
a
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ed
Descriptions
October 9th, 1995
DETAILED SECTION DESCRIPTIONS
VIDEO DATA PATH
2-19
