Summary : Color Postscript

Date: Tue Apr 23 1991 - 13:34:24 CDT

I was asking for inexpensive color postscript solutions, and here is a summary
of the information sent to me.

First, let me quote from an informative message about color printer
technology, from apunix!phb@UCSD.EDU (Peter H. Berens).
For color printers, there are a few choices you have to make.
There are basically two print technologies --- Thermal Transfer
and Dye Sublimation. Thermal Transfer produces 300 DPI color images
as long as you are using primary colors (YCM) or whole combinations
of primary colors. When you use arbitrary colors it starts using
an 8 by 8 dither pattern thus dropping you to 100 DPI effectively.
Thus a picture with arbitrary color will look very "dotty" close up.

Dye sublimation, on the other hand, starts out only at 150-170 DPI, but
it produces arbitray colors at that resolution by laying down the appropriate
mix of ink dots and then subliming them together into one color dot of
arbitrary 24 bit RGB value. The net effect is that for arbitrary colors,
dye sublimation printers look higher resolution that thermal transfer.
In fact, they appear to be very near photograhic quality.

There is, of course, a difference in cost. Thermal transfer printers
are in the 7-8K price range. Full page dye sublimation printers are in
the 15k price range. Near full page formats (8 by 10) can be had in
the 7-8k price range, however. For presentation graphics (charts, graphs,
text) thermal transfer is very good as you can force everything to
good color choices and you have higher resolution.
For color picture rendering, dye sublimation is far superior.
Cost per page is about $1-2 for thermal transfer and about $3-4 for
dye sublimation.

Most thermal transfer come with either RS-232 or Centronics parallel and
are PostScript based internally. Thus they are 100% NewsPrint
compatible regardless of which interface you use. The Dye Subs are
generally either Centronics or SCSI based. Both rely on NewsPrint
to do the postscript conversion and thus require NewsPrint "drivers".
We supply these for the dye subs we support. One thing to keep in mind,
however, is that if you are printing raster images then the PostScript
model is exteremely inefficient and time consuming. It can take up
to 20-40 minutes to print a full page raster image over the RS-232
(or even parallel port for that matter) in PostScript form. In
native print mode of the printers, the raster image can normally be
transfered and printed in just a few minutes. There is some talk about
PostScript Level 2 printers being somewhat faster at this, but we have
not seen any in-house so far.
The vendors I heard about are:
1) QMS - one person complained about image quality, others had no problems.
2) Seiko, sample configuration:
        CH5504-PM3* A-Size Color Printer fromm Seiko $6,395
        C3-CEN-10 10 ft. Parallel Cable, Centronics to Centronics $25
        NS-2034021 Color Printer Server for Seiko Printer $3,356
        CH721U Three Color Ink Sheet; 1 Box of 4 Rolls $280
        CH811U Copy Paper; 1 Box of 4 Rolls $30
        CH901H OHP Film; 1 Box of ! Roll $88
(Seiko was or is running a promotion associated with NEWSPrint, which may
lower the price significantly from their list prices)

3) Tektronix - Phaser II SX - uses cassettes, rather than rolls of paper
4) General Parametrics SpectraStar 430 PostScript Thermal
Transfer printer. 300 DPI resolution, 16.7 million colors, and 35
resident fonts. Supports 1,3, or 4 color printing. It has an Intel
80960 RISC controller with 6MB RAM. RS-232, parallel and Apple talk
interfaces. It prints one page per minute. Available from apunix. $6758.

5) Mitsubishi (formerly Shinko). No price given

6) HP PaintJet, 180 dpi (less with dither), driven by ghostscript (with some
patches for the HP PaintJet) 3-4 minutes/page, order with either serial or
parallel interface $875
   HP PaintJet XL (can use cut-sheet paper) 1.5 - 2 minutes/page
    has both serial and parallel interfaces. $1535
                                                (government pricing)

7) Kodak - rumored to be about $10K, but 100 or 150 dpi with real color w/o

 In response to my other questions:

 1) Yes, NewsPrint can be used over a serial port, although some software work
may be required. Speed is a real problem, though.

Thanks to all who responded. As usual, I got lots of useful information, very

        Joe VanAndel
        NCAR - ATD/RSF
        P.O Box 3000 Fax: 303-497-2044
        Boulder, CO 80307-3000 Voice: 303-497-2071

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