Re: Grainy Laser Profiles
Re: Grainy Laser Profiles
- Subject: Re: Grainy Laser Profiles
- From: Karsten Krüger <email@hidden>
- Date: Tue, 27 Jun 2006 09:45:04 +0200
This can not be generalized. It highly depends on the printing
technology and the paper being used.
The "noise" comes from uneven electrostatic behaviour of the paper.
When mixing colors directly on the paper (used by older technologies)
the paper has a strong influence. Only specially treated paper will
give decent results (i.e. ColorCopy/Colotech brands). In this case
reducing CMY and adding K will lead to better results.
Modern printers use indirect printig. They have a "digital web" which
accumulates all ink, and have a one step transfer to the paper. The
quality related electrostatic process ist between the drumm(s) and
the web, which does not have issues like paper. The quality of the
paper has only little influence, allmost any type of paper (coated,
uncoated, recycling) can be used. It just has to be heat resistant
for the fuser.
An other aspect is the raster being used. There are 2 types: line and
dot. Line raster usually addresses about 600dpi and has halftoning
(theoretically 256 steps of ink on the paper), while dot uses the
same process like offset (collecting dots into a haltone cell). Line
raster usually gives more details in pictures and small text, but
showing stronger noise in areas of solid colors. Dot raster is not as
sharp and detailed as line raster, but has smooth solid colors
without noise. Line raster has an other issue - depending on the
print engine colors like to shift during production, especially in
highlights (less than 20% of ink).
If a printer is able to produce more than 1200 dpi, dot raster is the
better choice in most cases.
With line raster less CMY and more K usually gives better results.
With dot raster at least the printers I know (high end Xerox) behave
allmost like an offset press - any real world (=offset) GCR/UCR
settings will work fine.
Karsten
Am 27.06.2006 um 08:59 schrieb Graeme Gill:
Karsten Krüger wrote:
Grain usually comes from rasterization. So first you should check
your printer settings.
An influence the profile can have is the black generation curve.
Many laser printers have "noise" in the printing process that
is analogous to, but different to screening or banding in
inkjet printers. The black ink has the highest contrast, so
a CMYK profile with a high level of black will tend to
exacerbate such effects. Just like inkjets, a laser printer
gets a smoother looking image if the CMY and K levels are
approximately equal for neutral colors.
Graeme Gill.
_______________________________________________
Do not post admin requests to the list. They will be ignored.
Colorsync-users mailing list (email@hidden)
Help/Unsubscribe/Update your Subscription:
40kkrueger.de
This email sent to email@hidden
_______________________________________________
Do not post admin requests to the list. They will be ignored.
Colorsync-users mailing list (email@hidden)
Help/Unsubscribe/Update your Subscription:
This email sent to email@hidden