QTR-Quadtone RIP

I had this problem for a long time and them moved to the 21 step wedge

Excerpt from my notes on curve creation:

-	IMPORTANT:
	--	Take the advice of Roy Harrington contained in the documentation  
(Eye-One-ReadMe.pdf) and generate linearization and Profiles using  
the QTR-21x4-random calibration file. In my experiments using the 51  
step target delivers less smooth transitions of the tone ramp which  
looks like posterization or strange lines along areas of subtle tone  
transition (shadows on cheeks, sky, clouds and out of focus  
backgounds.) This is either because there are just too many data  
points on the linearization curve, thus creating flat spots, or due  
to the fact that there can be small inaccuracies in the readings of  
the Eye-One which results in an un-smooth curve.I have had several  
instances where the Eye-One delivered inaccurate readings that  
resulted in bad linearizations. If I sense that something is strange  
in the look of the sample display (two patches in the Measure Tool  
interface seem too close in tone and don't seem to correspond with  
the look of the test page, then I either re-read the patches, or save  
two output files from two different measurings of the target, and  
then compare the data, even pasting the data into Excel and making a  
chart of the data to see the curves. This has been tedious, but very  
helpful in resolving issues and learning exactly what is going on.  
For this reason as well, I use the QTR-21-gray file and not the  
QTR-21-random target. It is easier to see if you are getting strange  
readings.

-	In a classic example of doing what I say and not what I do, after  
wrestling with this issue for a week I re-read the Eye-One-ReadMe.pdf  
file and Roy clearly recommends says
	--	"The 21x4 target is recommended for the best accuracy. It has 4  
patches for
each step value and the QTR software will automatically average the 4
measurements which gives a more accurate result."
--	I am a believer now. Save yourself the pain, follow the instructions.


On Dec 5, 2007, at 6:15 PM, Louis Dina wrote:

> Eric,
>
> I had the same problem awhile back. Apparently, QTR looks
> for "enough" tonal difference between steps before it will accept a
> file for linearization. If the tones are too close together, or if
> there is a reversal anywhere, it rejects the input file.
>
> Try the 21 step wedge for linearization. To me, the 51 step is
> probably overkill, and besides the differences are even smaller on
> the 51 step wedge.
>
> Lou
>
> --- In QuadtoneRIP@yahoogroups.com, "E Neilsen" <e.neilsen2@...>
> wrote:
> >
> > 0.00 0.06 0.09 0.11 0.13 0.14
> 0.15 0.16
> > 0.17 0.18 0.20 0.21 0.22 0.24
> 0.26 0.27
> > 0.30 0.34 0.37 0.42 0.46 0.51
> 0.57 0.62
> > 0.67 0.75 0.79 0.84 0.93 0.97 1.03
> > 1.10 1.13 1.17 1.25 1.26 1.30
> 1.38 1.40
> > 1.46 1.53 1.57 1.61 1.69 1.73 1.77
> > 1.84 1.88 1.91 1.95 2.00
> >
> >
> >
> >
> >
> > I am unclear why I can't get my linearization to take.
> >
> >
> >
> >
> >
> > Eric Neilsen Photo
> >
> > 4101 Commerce Street, Suite 9
> >
> > Dallas, TX 75226
> >
> > 214 827-8301
> >
> >
> >
> > http://ericneilsenphotography.com
> >
> > SKype ejprinter
> >
> >
> >
> >
> >
> >
> >
> > [Non-text portions of this message have been removed]
> >
>
>
> 



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