QTR-Quadtone RIP

Mike,

I think the issue is that to some a change in "a"  or "b" of say 1.4 is
not noticeable and to others it is.
Also we are more sensitive in midtones and less in shadows. It's all very
subjective.

As a guideline I would have a look at what Paul Roark is achieving in terms
of a,b values for b&w and what he finds acceptable.
www.paulroark.com

Mike

On 28 April 2011 17:30, Mike Finley <mike.finley@...> wrote:

>
>
> no-one?
>
> On 15/03/2011 18:22, Mike Finley wrote:
> >
> > So far, I've not had to create new curves, just tweak existing ones for
> > similar papers. Now I've switched to an Epson 3880 and it doesn't have
> > many existing papers to start from, so I'm trying to figure out how to
> > create my own curves, starting with a glossy paper (innova fibaprint
> > white gloss).
> > I've printed a 21 greyscale patch and read the Lab values, and am now
> > not sure how to interpret them.
> >
> > L I'm not bothered about ... linearising should clean that up easily
> > (its pretty good to start with) but am not sure how to interpret the a
> > and b values:
> >
> > a starts from a low range of 0 to 0.4 (meandering) up to the 50% ink
> > point, then rises steadily to 1.6 at 70% ink, and then to 1.8 at 90% ink.
> > b varies up and down over a range of 1.5 to 2.4 (the paper white is
> > 1.5). As there's not much of general progression, more meandering up and
> > down, it seems I'll just have to take this as reasonable.
> >
> > Being partially colour blind, its not easy for me to judge the impact! -
> > are these significant (this is supposed to be the neutral curve) or
> > should I try to at least reduce the a ramp, by reducing the magenta
> > content a little
> >
> > Thanks for any insight ...
> >
> > mike
> >
> > --
> > mike finley photography
> > http://www.mikefinley.co.uk
> >
> >
>
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>
>  
>


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