QTR-Quadtone RIP

Hi Jason,

I must confess I can't precisely visualize the tone of 
palladium/platinum prints, but given your description I'm not 
surprised the standard QTR curves are of little help. Greenish tones 
are not often sought for. 

In practice, The variation of tones is done mostly along the Lab b 
axis (warm-cold or yellow-blue). Occasionally, depending on the ink 
set, one finds a selenium curve (I'm currently working on one for a 
particular paper) that allows vary into positive Lab a values (red), 
adding more magenta. 

But what you need is a curve into the negative Lab a values (green). 
With the OEM inks that should be possible, but you will have to 
create that yourself. And you need a spectrometer to do so. I expect 
such a curve to need ample of yellow, something that most of us here 
are avoiding, giving the relatively low archival quality of yellow 
pigments. 

I could see two ways to proceed. The simplest and most flexible way 
is to builds a pure greenish QTR curve (with a tone of around Lab a 
= -5 to -7, depending on the paper). This will be too green for your 
taste, but the idea is to use the QTR Curve blending feature to blend 
it with a warm curve. 

Perhaps a more "purist" approach would be to figure out what the 
tonal scale of palladium/platinum print looks like (in terms of Lab a 
and Lab values for varying L) and create a dedicated QTR curve 
working towards that. If you would by chance have print of a 
stepwedge avialable that would be fairly simple with a spectrometer. 
If not, I guess picking local values out of a standard print could 
work as well.

So, my feeling it is much very do-able, but it requires a 
spectrometer and some digging into QTR.

Joost

>
> I've been experimenting with QTR on a R2400 using stock Epson inks 
to simulate the 
> yellow/greenish look of palladium/platinum prints.   The "warm" 
curves provide the most 
> yellow contribution.  However, I'm finding that with the provided 
curves I really can't get 
> close.  The result does not have enough tint and has muddy clogged 
up shadows.  My 
> biggest concern is the low tint saturation.  I've found that 
printing a color-tinted image 
> using the Epson driver in color-mode gets me closer.   I'm a 
digital photographer and would 
> really like the exhaust the possibilities of a digital simulation 
before I consider the real deal.  
> Is my goal possible with QTR?  Does anyone have curves more 
suitable for emulating 
> platinum/palladium?
>    
> Thoughts?
>