How does one find and use the low-level color calibration functions of
a Postscript dye-sublimation printer?  Specifically, how can one find
the control points which adjust the dye intensity for each requested
intensity of CMYK?

I have a mitsubishi S6600-40, a Seiko Colorpoint 830PS, and a
Tektronix Phaser 480x.
On the Phaser 480X, there are functions 'setcolorcalibration' and
'currentcolorcalibration' in the ColorCalibration directory in the
ProcSet
resource.  These take or return a 4-item array of 16-entry arrays
which
hold what are apparently intermediate values in [0-255].
By printing a sample sheet as CMYK with 18 values per color and
reading
the resulting sheet with an X-Rite spectrophotometer, I was able to
set
the array such that the printer output now corresponds very closely to
Lab color input.  This array is apparently stored in non-volatile
memory
since setting it once in privileged mode (startjob) was sufficient.

I would like to do this with the other (Mitsubishi and Seiko)
printers.
I have not been able to find anything relating to calibration in the
Mitsubishi.   The Seiko has a 4 x 256 array  which is initialized to
a linear (0-255) value for each of the 4 components.  The Seiko values
do not appear to be stored in nonvolatile memory but are regenerated
in the system initialization postscript code.

Is there a likely thing to try on the mitsubishi printer?
Is there an alternative name or approach to calibrating the color
output
which I have not seen?  Using "setcolorrendering" is possible but has
problems since .eps files often override this, and some even go so far
as to bypass redefinition of that operator by looking in systemdict.
Also, it is not clear that setcolorrendering works late enough in the
rendering process.

omnivore,

I contacted a support person Mitsubishi, who said:

"The model printer you have is a Postscript Printer. There should be
no need for color calibration sine the Postscript Language should take
care of any mismatches. If the color is very bad you may have a
printer problem. If so, you will have to send it to the Factory Repair
Center repair. Their tel # is 800 446 6866."

I have a feeling that this isn't quite what you wanted to hear. If you
have a clarifying question, I can pass it on to the support person.

I hope this helps at least a little,
waffle-ga (a herbivore)

I asked for clarification, and he wrote: "There is no way to adjust
color with Postscript. You will have to make any color adjustments
with your applications."

Waffle, I don;t belive that is always true. I have used postscript
dye-sub printers like Kodak and Codonics, for example, that have gamma
and contrast controls and allow you to adjust the color in that
manner.

I believe that is what omnivore is looking for on this particular
printer.

And postcript will not automatically adjust for different paper ofr
media such as transparency. Which is why these controls are necessary.

I think you reached a misinformed rep at Mitsubishi.

-=clouseau=-

Well, I must have reached the same rep at Mitsubishi that you did,
waffle :) He claims that with Tektronix, Kodak and Codonics the
settings are acheived with a very expensive 3rd party software app
that makes these changes. That is patently not true as I have printed
thousands of images on those printers and the settings are control
panel accessable, at least on the Kodak engined printers. And similar
on the Tektronix if I recall correctly.

Be that as it may, he claims there is no way to set gamma or contrast
on the Mits printer other than in the application. And Seiko doesn't
seem to support their printer in the US. At least, my search was
unable to turn up any division that would lay claim to supporting this
model Seiko.

-=clouseau=-

Further comments from my support rep: "I checked with our engineers
and confirmed there is no color adjustment internal to the S6600-40
printer. All color adjustment is done in the application before it
makes a postscript file up to send to the printer. The postscript file
contains all the color info for the postscript processor built into
the printer. If the colors are not correct you will have to use your
applications to adjust the color the way you want."

Thanks very much to both of you - I hope to be of help to  you in the future.
It looks like any color corrections will  have to be done  by downloading
the color rendering functions and making adjustments to the rendering tables,
a daunting task, or by setting the color transfer functions, which is difficult
in another way.  Oh well, if it were simple anyone would  do it!
    thanks!