QTR-Quadtone RIP

I am a newbie trying out QTR on a R220 using UT-R2 inks.  Since there are no curves available for that ink set, I am trying to set up my own.

I have printed the calibration sheet, and following the help file, and the user guide I am still unclear on how to set the densities in the curve creation stage.  The example given in both files describe a two ink example.  UT-R2 inks contain three densities - two gray inks in addition to the black ink.

Setting the density of the first gray (LK) is pretty clear.  Try to match the density in the black (K) step wedge to set the 100% gray density as a proportion of the black step wedge.  For the lighter gray (LLK) repeat.  

The question I have is for the LLK density, does one enter the comparative density as read off the K step wedge or the comparative density as read off the LK step wedge?  i.e with the K ink density set at 100%, the 100% LK density in my test strip was 43% of the K step wedge.  The LLK density was 40% as compared to LK and 28 % as compared to the K strip.  Which value do I use in the curve creation process for the density of LLK (40 or 28)?

Also, the UT-R2 inks consist of only three gray inks - K, LK and LLK.  The R220 is a hextone printer, so the other three cartridges contain duplicate inks  i.e.  The cyan and magenta cartridges contain the same ink (LK) and the light cyan, light magenta, and yellow all contain the LLK density ink.  In setting up the curves, should one disable the duplicate ink cartriges, or use the "copy from" method in setting their densities and limits?

lebleur wrote:
...
> 
> Setting the density of the first gray (LK) is pretty clear.  Try to
> match the density in the black (K) step wedge to set the 100% gray
> density as a proportion of the black step wedge.  For the lighter
> gray (LLK) repeat.
> 
The way I do it is to determine where the 100% LLK matches the LK and 
then apply that percentage to the LK to K percentage. For example:

LK 100% matches K 45%
LLK matches LK 30%

Therefore limits:
K 100%
LK 45%
LLK 13.5% (30% x 45)

I'd be interested to hear other methods. To be honest I usually find 
this method gives a slightly too dark end result so I usually end up 
backing off the ink limits a tad to get the unlinearised curve as close 
to optimum as possible.

> The question I have is for the LLK density, does one enter the
> comparative density as read off the K step wedge or the comparative
> density as read off the LK step wedge?  i.e with the K ink density
> set at 100%, the 100% LK density in my test strip was 43% of the K
> step wedge.  The LLK density was 40% as compared to LK and 28 % as
> compared to the K strip.  Which value do I use in the curve creation
> process for the density of LLK (40 or 28)?
> 
Using my method
K 100%
LK 43%
LLK 17.2%

> Also, the UT-R2 inks consist of only three gray inks - K, LK and LLK.
> The R220 is a hextone printer, so the other three cartridges contain
> duplicate inks  i.e.  The cyan and magenta cartridges contain the
> same ink (LK) and the light cyan, light magenta, and yellow all
> contain the LLK density ink.  In setting up the curves, should one
> disable the duplicate ink cartriges, or use the "copy from" method in
> setting their densities and limits?
> 
> 
Yes, you could use Copy curves to duplicate the respective positions. ie 
set magenta to Copy Curve C, etc. On the other hand you could buy the 
UT-R2N set, put the LK & LLK in the M & LM positions and then be able to 
have warm & neutral curves in the printer at the same time. You could 
then even add UT7 sepia or a toner ink of your choice in the Y position.

Howard

--- In QuadtoneRIP@yahoogroups.com, Howard Shaw <glassman@...> wrote:
>
> The way I do it is to determine where the 100% LLK matches the LK and 
> then apply that percentage to the LK to K percentage. For example:
> 
> LK 100% matches K 45%
> LLK matches LK 30%
> 
> Therefore limits:
> K 100%
> LK 45%
> LLK 13.5% (30% x 45)
> 
> I'd be interested to hear other methods.

I use a different approach.  My 2200 only has two blacks - MK and LK.
 I do not set the default ink limit at all; instead, I set the MK
limit at 70% based on measurements.

My LK is about 25% of BK in Density, so that's what I set.  However, I
do not set the limit for LK, as I want the printer to use LK wherever
possible, to minimize the graininess.

I then apply linearization, and get very good results.

Dominic wrote:
> --- In QuadtoneRIP@yahoogroups.com, Howard Shaw <glassman@...> wrote:
>>
>> The way I do it is to determine where the 100% LLK matches the LK and 
>> then apply that percentage to the LK to K percentage. For example:
>> 
>> LK 100% matches K 45%
>> LLK matches LK 30%
>> 
>> Therefore limits:
>> K 100%
>> LK 45%
>> LLK 13.5% (30% x 45)
>> 
>> I'd be interested to hear other methods.
> 
> I use a different approach.  My 2200 only has two blacks - MK and LK.
>  I do not set the default ink limit at all; instead, I set the MK
> limit at 70% based on measurements.
> 
> My LK is about 25% of BK in Density, so that's what I set.  However, I
> do not set the limit for LK, as I want the printer to use LK wherever
> possible, to minimize the graininess.
> 
> I then apply linearization, and get very good results.
> 

Sorry, I used the wrong terminology - where I said limit I meant density.

I guess effectively you are setting a 100% ink limit on the LK. When you 
say LK is 25% of MK do you mean LK on your 100% or 70% calibration strip?

Howard

--- In QuadtoneRIP@yahoogroups.com, Howard Shaw <glassman@...> wrote:

> 
> Sorry, I used the wrong terminology - where I said limit I meant
density.

Actually the example in the User Guide (Figure 7) does limit LK to
50%; that's the part that I deviate from the User Guide.
 
> When you 
> say LK is 25% of MK do you mean LK on your 100% or 70% calibration
strip?

Actually it doesn't matter.  At 100% overall ink limit, 100% LK
matches 25% MK.

If the overall ink limit is reduced to 70%, the maximum LK is reduced
to 70% of its previous value, and 25% MK is also reduced to 70% of its
previous value.  The two still match.

In subsequent tests, I keep the overall ink limit at 100% but limit MK
to 70%.  In that case, matching of LK will have to be done relative to
100% MK scale, not the reduced MK scale.

Dominic

I cannot find the answer to what is probably a dumb question:

In using the step wedges to set the limits for the different inks,
should I use step wedges printed at 100% or step wedges printed with
an ink limitation setting equal to the default setting for Black that
I intend to use when I create the curve?

At 100%, everything on the black wedge beyond about 55% is full black.
 So I printed a calibration sheet at 55% and it looks about right
(though I will check it to make sure that I am getting 100% black at
the right end).

Assuming that 55% is right, then which sheet do I use in doing the
rest of the work?  Logic suggests the 55% sheet, but I'd like to get
this right so I decided to bother you all about it.

Thanks, and please forgive if the answer is in the User Guide and I
missed it.

If you mean the Ink separation patterns that you get using the 
calibration mode, then yes, you print that again using the 55% that 
is right for your set up and use that to set your additional limits.

Peter


--- In QuadtoneRIP@yahoogroups.com, "brunnerjd" <iconomat@...> wrote:
>
> I cannot find the answer to what is probably a dumb question:
> 
> In using the step wedges to set the limits for the different inks,
> should I use step wedges printed at 100% or step wedges printed with
> an ink limitation setting equal to the default setting for Black 
that
> I intend to use when I create the curve?
> 
> At 100%, everything on the black wedge beyond about 55% is full 
black.

>  So I printed a calibration sheet at 55% and it looks about right
> (though I will check it to make sure that I am getting 100% black at
> the right end).
> 
> Assuming that 55% is right, then which sheet do I use in doing the
> rest of the work?  Logic suggests the 55% sheet, but I'd like to get
> this right so I decided to bother you all about it.
> 
> Thanks, and please forgive if the answer is in the User Guide and I
> missed it.
>

Yes, you would use the 55% sheet and not a dumb question at all.

Tom

On 1/3/07, brunnerjd <iconomat@...> wrote:
>
> I cannot find the answer to what is probably a dumb question:
>
> In using the step wedges to set the limits for the different inks,
> should I use step wedges printed at 100% or step wedges printed with
> an ink limitation setting equal to the default setting for Black that
> I intend to use when I create the curve?
>
> At 100%, everything on the black wedge beyond about 55% is full black.
> So I printed a calibration sheet at 55% and it looks about right
> (though I will check it to make sure that I am getting 100% black at
> the right end).
>
> Assuming that 55% is right, then which sheet do I use in doing the
> rest of the work?  Logic suggests the 55% sheet, but I'd like to get
> this right so I decided to bother you all about it.
>
> Thanks, and please forgive if the answer is in the User Guide and I
> missed it.
>


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