mdc@indetech.com (Mark Copple ) (10/12/89)
I have seen several products that claim haltoning on the HP LJ II. The claims are
roughly this: The halftoning is accomplished with a full length Interface
card that resides in the PC, as small card that plugs into the HP LJ video port,
and a calbe connecting the two. The controler and interface card along
with supplied software allow for 300(verticle) x ~1200(horizontal) resolution.
One would think that the limitation of a laserprinter would be that of the
smallest possible focussing of the laser (which should be 1 diameter of the
lasers wavelength) But in reality it is consists of several factors.
Memory: It requires on bit of memory for every displayable bit onthe paper
Mechanical: The maximum rate at which the laser can be scanned
horizontaly across the page (thus the vertical resolution)
Beam modulation: The speed at wich you can turn on and of the laser as it is
scanned horizontaly. (Horizontal resolution)
I am not aware of anyone changing the vertical resolution I get the impression
that that is a hardware limitation of the current popular print engines.
What the Halftone cards are apperently doings is using the direct video port of
the HP so that they can attain the needed horizontal resolution my controlling
the beam modulation with the (In-PC) controller card. Since there is usually
a great deal more information in 6 and 8 bit deap tiffs, etc they then do
the image conversion either in the PC's local extended/expanded ram or on the
interface cards memory (if provided, in either case it is stil expanded)
Now as to how it looks.. It looks GREAT!! The images i have seen come out of
the appropriately configured printer is breathtaking! If you do document
publishing that requires alot of pictures in it By all means get one of the
half toning systems.
So far i am aware of at least 2 systems
Intel Corp (800) 538-3373 Visual Edge
Tall Tree Systems (415) 493-1980 Jlaser5
I dont currently have prices on either, but the numbers above will get you
to those In The Know
Enjoy
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