Canon CANOSCAN FB330 series Service Manual page 63

5. Resolution conversion
1) Resolution conversion in the horizontal scanning direction
Basic resolution of CanoScan FB330P is 300 dpi, and selective at 300 dpi, 150 dpi, 75 dpi.
Basic resolution of CanoScan FB630P/FB630U/FB636U is 600 dpi, and selective at 600 dpi,
300 dpi, 150 dpi, 75 dpi. Resolution conversion in the horizontal scanning direction is
performed by thinning the image data of the basic resolution.
Example: To decrease the resolution to 1/2, image data is output every other pixel.
2) Resolution conversion in the vertical scanning direction
The CPU changes the scanning unit moving speed to change the resolution in the vertical
scanning direction. When increasing the resolution, the scanning unit moves at a slow speed
to read more lines as shown in Figure 2-25.
COPYRIGHT © 1999 CANON INC. CANOSCAN FB330/FB630 SERIES REV.0 OCT. 1999 PRINTED IN JAPAN (IMPRIME AU JAPON)
A B C D E
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Figure 2-23
Sampling point
Moving direction
Scanning unit
Figure 2-24
Sampling point
Moving direction
Scanning unit
Figure 2-25
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