Why a Rasterizer ?

  • Thread starter Thread starter Talal Itani
  • Start date Start date
However, it's worth noting that, unlike many lasers and imagesetters,
These million dollar machines should be true to their quoted
resolution. They aren't inkjet. But they can be expected to use
halftones. One key reason for this is that many paper/ink conbinations
have a minimum effective dot size. They may not be suitable for your
highly specialised application. Indeed, it's hard to imagine that
ordinary paper can deliver at all. Printing on photographic paper with
an imagesetter may deliver what you need.
Click to expand...

Thanks. This is very true. I am giving up on printers. You are right,
imagesetters are expensive, and they are hard to own. When I use an
imagesetter service, the cost per sheet is high, and there is the hustle of
sending files and receiving the output, and the cost of mailing. Maybe I
can find a 'small' 'easy to own' 'inexpensive' imagesetter, yet maybe that
is impossible. I always outputted to film. I wonder if I can output on
white paper.
 
Printing on photographic paper with
an imagesetter may deliver what you need.
Click to expand...

Caveat: I'm not an expert on this sort of thing, and you probably need
to find one before investing the serious money needed.
 
I'm not sure you are understanding the printing process for inkjet
printers fully.

There are several differing inkjet printing technologies used. For
instance, Canon and Eposn do not use the same methodologies/

The Canon printer uses a thermal head which literally heats the ink at
the very tip of the head and when it boils that change of state causes
the gaseous state to provide pressure to expel a droplet of ink to the
paper. This method doesn't allow for much variation in dot size. As a
result, Canon heads (depending upon the model) have three sets of
nozzles. The very small dots you speak of are not produced by the same
ink nozzle as the larger ones are. A larger dot is used to create
larger denser areas of color.

The Epson head, as one example, is called a piezo mechanism. Unlike the
Canon, it is a cool (as in temperature) method that involves the piezo
actuator vibrating and that frequency causes the fractionation of the
liquid ink which is then expelled through the nozzle in the head. In
the case of Epson printers each nozzle is used for between 3 and 7 drop
sizes, depending upon the model specs. The nozzle is large enough to
allow even the largest dot size to get through as well as much smaller
ones.

Art


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OK, I stand corrected. I wasn't sure, which is why I prefaced my remark with 'AFAIK'. Thanks for the enlightenment.
 
[A complimentary Cc of this posting was sent to
Talal Itani
ok. That made sense to me. Inkjet printers, like the Canon I have, have a
resolution of 4800 x 2400 dpi. When I use a loupe, I can see the very very
tiny dots. The dots are tiny when the colors are light. When the colors
are dark, the high-resolution is not maintained. This is because the rip of
the printer is very powerful, and the rip cannot address every single dot
individually. I have a project that requires high-resolution, and being
able to address every single dot individually. I learned that a separate
RIP can be purchased for this task. Do you know more about this?
Click to expand...

I can't give you the exact answer (and the answers you got here do at
least look "very reasonable"), however, I want to point you to either
some code which DOES work directly with "dots" (as opposed to
"pixels") of a printer, or the people who wrote this point.

Take a look at
http://gutenprint.sourceforge.net/gutenprint-users-manual.pdf

In particular look at the last clause of 6.1.8, (8):

Applications with special requirements can now access the raw ink
channels directly. This facility was used to create a mechanism to
more accurately tune printer inks.

Looking around this page (p.41), one can guess that this code may be
accessing ink drops more or less individually. I would guess that
using (some modification of) this code, one could position drops with
the granularity restricted by hardware only. (Moreover, looking at
the code, you might be able to find out what are EXACTLY the
limitations of the hardware.)

[Keep in mind that other answers in this thread discuss more or less
limitations of HARDWARE + THE PRINT DRIVER. The code above may
have fewer limitation.]

[Disclaimer: I myself did not look at the code in question, only
looked through the user docs. Better try to contact developers
first...]

Hope this helps,
Ilya
 
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