User manual

98.05.08.09.00
Color LaserWriter 12/600 PS Troubleshooting 2–33
Print Quality Issues
This topic addresses general print quality defects that can occur in the
Color LaserWriter 12/600 PS. Since color quality is largely subjective
and some nuances are nearly impossible to describe, we encourage you
to familiarize yourself with all the general issues covered in this topic.
To learn general principles of color theory, go to the “Interactive Color
1.6” folder that is bundled on Service Source CD. This application
requires a color Macintosh with screen resolution of 640x480.
Note: Best quality paper will yield best results. If color matching is
critical, discourage customers strongly from using colored or off-white
paper. Avoid recycled paper, if possible.
1 Live text prints fine, but equivalent bitmapped text sometimes prints
blurry and exhibits a fuzzy halo effect. What is the problem?
When an object gets a full saturation of two colors, the haloing effect
normal to all laser imaging is compounded. To offset this, the I/O
controller checks incoming fonts and decreases their saturations
slightly in cases where unacceptable haloing would otherwise occur.
For example, a green font (pure cyan with pure yellow) might be
adjusted to 80% cyan and 80% yellow. This adjustment does not visu-
ally alter the color.
Since font ID drives this process, bitmapped text is ignored and is
imaged as a normal graphic. To offset haloing in graphics, you must
make adjustments by hand in the source application.
This same process allows live black text to be imaged in black toner
only, instead of 100% saturation of cyan, magenta, and yellow. Live
text will be extremely sharp; graphic text will tend to be blurry.
2 We have two Color LaserWriter 12/600 PS printers and we get slightly
different colors from them. Is there any way to adjust them?
The printer is adjusted at the factory to produce the best possible image
quality. If you want to change from these defaults, see “Density
Control Panel” in Chapter 1.
3 I am getting some banding on my prints.
The term “banding” is generically defined as nonuniform density along
the length of the page, and usually appears as some kind of horizontal
print defect. Banding can very difficult to measure but is easily
discerned by the human eye.
Banding caused by electrophotographic and high-voltage processes has
been minimized in this printer, but will appear in some cases. This
banding is a natural function of digital imaging and cannot be
completely remedied.