Canon BJC-55 Series, Service Manual

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2.2 720 dpi Printing/Smoothing Feature
2.2.1 Canon extension mode
In Canon extension mode, the printer driver creates 720 dpi data for the horizontal
axis and sends it to the printer, allowing the printer to archive high-quality printing.
With a black BJ cartridge installed, the printer driver smoothes the printed
character's edges to 720 dpi along the horizontal axis. The 720 dpi data for the
horizontal axis is sent to the printer and the edges are smoothed at a higher
resolution.
When a color BJ cartridge is installed, a 360 dpi data is represented by a set of two
dots printed simultaneously to obtain a 720 dpi resolution. The multi-value data of
the pixels processed by the printer driver for color correction, etc., is assigned three
values (no printing, single-dot printing, two-dot printing) for each pixel. In the case of
two-dot printing, the second dot is printed in the 720 dpi position. As a result, this
method enables the printer to archive high degree gradation printing.
2.2.2 Emulation mode
When a black BJ cartridge is installed, the printed character's edges can be smoothed
at a high resolution of 720 dpi along the horizontal axis. Dots along the character's
edges are added or deleted to smooth their edges. Along the horizontal axis, dots are
also overlapped by half a dot. This eliminates jaggies and doubles the equivalent
horizontal resolution.
This smoothing feature greatly improves low-resolution, 180 dpi characters. However,
it does not give noticeable improvement to TrueType fonts and illustrations.
Note that with a color BJ cartridge installed, the emulation mode smoothing feature
cannot be used.
4-15
BJC-50
Part 4: Technical Reference
BJ
1/720 inch
Add Dots
Delete Dot
1/360 inch 1/360 inch
Figure 4-12 720 dpi/Smoothing Function