Yahoo Groups archive

Digital BW, The Print

Index last updated: 2026-04-28 22:56 UTC

Message

Re: [Digital BW] QTR and Making Curves

2003-12-22 by Steve Kale

Carl

Thanks as always.  A couple of follow-on questions...


<snip...

There could be printer differences, Eye-One (or other instrument)
differences, or differences in drying time before measurement.  This
why it is a good idea to do your own linearization.>

Ok but you would agree that I am at least following the right procedure
here?


<snip...
> 2) K is limited to the default limit which is 75.  Why?
Measured as described in step 1 of the calibration procedure.>

Ok I have just now seen the Calibration.rtfd file and will work through it.
I started with Getting Started which cross refs the Ideal Density, Eye-One
and CurveInfo files but not Calibration ­ it simply says _the two
calibration steps below_ but there is no Calibration below in that file.  I
guess I will likely have a few more questions.

> 3) Why is LK limited to 56 (cool)/ 60 (warm)?
You answered this question in #4 below.

Sorry my point was why around this level in the first place (in 4 I was
simply referring to the cool curve having a slightly lower figure than the
warm).


> 4) I assume the limits for LC and LM need to be the same to balance
> against
> metamerism and that LC and LM are used to cool the Epson K and LK (and
> I guess it
> follows that one might lower the LK limit a little in the cool file).
The idea was to adjust LC and LM, relative to LK,  to produce a very
cool curve that could be used for blending with the warm curve to
produce the desired tone.
>     Is a cool curve is
> one that takes the warm and at 50:50 is neutral?
It could be adjusted to do so, but perfect neutrality at 50% would be
fortuitous.
>
> 5) If so, how does one measure neutral?
You could use the LAB or XYZ values from the Eye-One to evaluate
neutrality.
>
> 6) Was the cool file created by steadily increasing the limit on LC
> and LM until this was
> achieved?
I wasn't shooting for neutral with the cool curve - just a very cool
curve that could be subsequently blended with warm to get the desired
tone.


I guess I need a little more guidance on how you determine you have obtained
a cool curve (or neutral combination).  That is, when you are working on
_adjust[ing] LC and LM, relative to LK_ how do you know you have reached the
goal of a very cool curve (and so there is no need to go further)?


<snip...
I think you may have overlooked the calibration read-me file that
describes the two step calibration procedure.>

Yes.

One further point.  I have to say that I for one would be happy if QTR
became paid-for shareware so that Roy, Carl et al were encouraged to take
the time to improve the documentation, make additional enhancements to the
interfaces etc.  At the moment the documentation is a little all over the
place and while the how is there, there isn¹t a lot of why.  A token sum per
individual user could add up to quite an incentive and I for one would be
very happy to make a contribution.  I guess charging, however little,
creates an onus for support but I suspect most of that is being provided
already.

Thanks

Steve






[Non-text portions of this message have been removed]

Attachments

Move to quarantaine

This moves the raw source file on disk only. The archive index is not changed automatically, so you still need to run a manual refresh afterward.