QTR-Quadtone RIP

Howard

Just to be clear, I understood what you were suggesting and I wasn't stating
the suggestion was a bad one. It just occurred to me that the underlying
assumption (that the C/M and LC/LM densities are close enough to permit
swapping) implied that one could make a normal (i.e. not split tone) warm
curve, linearize it and then create a cool curve by simply swapping inks.
That means less work and therefore interesting - to me at least.

What puzzled me was that the warm and cool curves (for HPR, for example) are
different. I got off the rails a bit when I mentioned toner curves - it was
late and I was tired. However, between the warm and cool curves, the
partitioning values are slightly different and the linearization values are
quite different. The curves for EEM have similar differences.

My question was, therefore, have you (or anyone else) actually tried doing
this - either to create a split-tone curve in the manner you suggested or to
create a warm from a cool curve without re-linearizing.

Tom Moore


> -----Original Message-----
> From: QuadtoneRIP@yahoogroups.com [mailto:QuadtoneRIP@yahoogroups.com] On
> Behalf Of Howard Shaw
> Sent: Sunday, October 08, 2006 3:54 AM
> To: QuadtoneRIP@yahoogroups.com
> Subject: Re: [QuadtoneRIP] Re: Split Toning with QTR
> 

...

> >
> If the inks have similar densities across the range at the calibration
> stage then they should be interchangeable without affecting the
> luminance scale. UT7-C & M & UT7-LC & LM were designed with this in
> mind. In reality the two cool inks are slightly darker than the carbon
> ones but the effect is barely noticeable and if it was bothersome
> nothing that a re-linearisation wouldn't sort out. I'm not sure what you
> mean about Toner Curves as none of the standard warm & cool UT7 curves
> use a toner curve.
> 
> There are many ways to do split toning in qtr - without even touching
> the toner curves the 'Load curves' and 'Copy curve from' facilites
> provide great flexibility. For example take the current standard Photo
> Rag Warm curve:
> 
> K, Gray Ink, Density 100, Limit 70
> C, Gray Ink, Density 47, Limit 70
> LC, Gray Ink, Density 15, Limit 70
> 
> You could change this to:
> K, Gray Ink, Density 100, Limit 70
> C, Gray Ink, Density 47, Limit 70
> LC, Gray Ink, Density 15, Limit 35
> LM, Copy Curve from LC, Density 15, Limit 35
> 
> The new curve would give warm carbon shadows & midtones moving towards
> more neutral highlights as the LM kicks in. I have halved the limits on
> the LC & LM so they both add up back to 70 as in the original curves LC
> alone. As we are replacing like for like no re-linearisation should be
> necessary.
> 
> Howard