QTR-Quadtone RIP

Hi Cody,

There are a lot of pieces.  You surely don't need to know in all right away.  Most people
just print with existing profiles and never bother with how profiles are made.  With an
Eye-One you have the capability to customize profiles for your system so it makes
sense to take advantage of that.   But it's unlikely that you need to redo everything.
There's two ways of looking at the whole process. First, a top-down approach that gives
all the details starting from scratch. But I think most of the time a bottom-up view is a
more practical method.  I.e. start with an existing profile and only redo the final steps
as you find a need to.

Here's an overview of the top-down steps:

1) Decide Ink Limits -- this is how much ink can you put on the paper without
overdoing it.    The main tool for this is the inkseparation page and printing in
"Calibration Mode".   This gives a raw stepwedge of each ink.  You mainly decide just
the gray inks here because you most likely want the max.  Toner inks will probably be
less, based on how much color tone you want.

2) Partitioning is dividing the grayscale range so lighter inks are used in light areas and
darker inks in dark areas.  Any number of levels are possible, you just need to tell QTR
the relative density.  This is also done with the inkseparation page in Calibrate Mode
printed with the correct ink limit.  Partitioning for toner inks is also possible.

3) Toner inks allow an almost arbitrarily flexible way to vary the color tone.  In general
I'd always start with a pure gray profile and then decide what color inks to add.  Very
often you can just copy gray curve shapes to the toner inks or you can set an arbitrary
toner-curve.  You vary the toner ink limits for the overall amount of ink.

4) Linearization is the final step.  The above steps ought to give you a smooth transition
from white to black.  However due to dot-gain and interactions between inks and paper
a gradient will be too dark/light in some areas.  Linearization measures the output and
then applies an overall correction curve to the grayscale.  The result should be a
straightline of L-values versus steps.

That's the basic QTR profiling method.  For most situations I expect just re-linearizing for
your printer or for different papers is all that is needed.  You just take out the existing
linearization values, print out the stepwedge, and input the new values.
If you want to tweak color more than Tone Blend allows you'll need to go back to (3).

All the info in the Eye-One folder is about automating the patch reading.  Reading one
patch at a time in density or Lab is fine but the MeasureTool program allows reading
a bunch of patches in one scan.  The Linearize-Data is just an aid to pull out the data
for easy editing.  Functionally, this is all about just reading data that will be edited 
into the QTR profile.

--------------

Finally, at the risk of some confusion, there is a completely new and independent
feature of ICC profile making.  All the above relates to QTR profiles that are used in
the QTR print driver.  ICC profiles are for the Color Management System in PS to allow
soft-proofing and embedded grayspace to print matching.  There are a lot of similarities
to the linearizing above.  In fact the same targets and reference files are used.  But
they are different -- QTR profiles in the driver allow Tone Blending which has no
counterpart in ICC color management -- ICC profiles allow soft-proofing and grayspace 
conversion which has no QTR counterpart.

In some sense you can look at this as step (5) in the process and the bottom-up
customizing can easily be done just here.

Hope this helps you get started.  In general, start simple, tweak only a little to you
get a feel of the effects.

Roy

--- In QuadtoneRIP@yahoogroups.com, "cteditions" <cteditions@a...> wrote:
>
> QTR Group,
> 
> I need your help please.  I have read ALL QTR documentation, including duplicate info 
for 
> addressing Mac OSX, and have a "general workflow confusion".  I understand all of the 
> details but the general workflow order of procedure seems to not be clear to me.  My 
set-
> up is as follows:
> 
> PowerMac G5 Quad 2.5GHz (OSX Tiger) 
> Sony Artisan GDM-C520K (Self Calibrating) Monitor 
> Epson R2400 Printer 
> Epson 4990 Scanner (Soon an Imacon) 
> Photoshop CS2 
> Gretag Macbeth Eye-One System 
> 
> 
> Is "Curve Creation" the same as "Calibration"? It seems as if going through the "Ink 
Limits" 
> process IS the "Calibration Process" wrapped within the "Curve Creation Process". Is this 
all 
> the same? Should the first thing one does in setting up QTR be to go through the "Ink 
> Limits" and "Partitioning" Processes? Do you simply print a chart from Photoshop using 
> QTR without a curve? 
> 
> THIS IS PART OF THE CONFUSION:
> 
> The "QTR Mini Tutorial for Mac OSX" goes through the Ink Limits, Partitioning, and 
> Linearization by using Text Edit and CurveDropBox, HOWEVER, there is a document 
called 
> "Eye-One Spectrophotometer with QTR 2.3" that goes through some kind of Calibration/
> Linearization/Profiling Process using MeasureTool from Gretag Macbeth. ARE THESE 
TWO 
> DOCUMENTS DOING THE SAME THING? The Eye-One document does not talk about Ink 
> Limit or Partitioning so I don't know if I need to do this separately first (manually with 
Text 
> Edit) or if the Eye-One does this automatically. 
> 
> Does using the Eye-One with MeasureTool TAKE THE PLACE of going through the 
process 
> explained in using Text Edit to create Ink Limits, Partitions, and Linearizations?? And 
> where should the final PROFILE be created.. with MeasureTool & Eye-One??
> 
> Sorry for this seemingly ridiculous inquiry but with all I have read I can't seem to pin 
down 
> a logical order (using Mac OSX & Eye-One) to set-up QTR in respect to calibration, curve 
> creation & Profiling.  Everything is installed correctly…
> 
> PLEASE HELP, I would greatly appreciate any feedback…
> 
> Regard,
> 
> Cody Thomas
>