QTR-Quadtone RIP

Roy,
    you are right.  Some of the profiles are very close, but none of 
them are quite right, it's maybe because I am using Lyson ultrachrome 
inks rather than the original Epson inks.

Maybe I am getting over-pedantic about going for a truly neutral 
print, but because I've got a spectrophotometer I can't help wanting 
to tweak it until it's just right. (As somoeone famous once said - A 
little knowledge is a dangerous thing!)

My problem is knowing which 'knob' to tweak and which way to tweak 
it.  For instance when I have put the spectrophotometer data throught 
the linearising tool I can see from the L*a*b* graph that I have too 
much blue in the shadows and too much red in the highlights although 
the midtones are pretty much spot on.

Am I better off trying to adjust the ink limits on the ink descriptor 
page or should I adjust the shadow, highlight and gamma values on the 
tone curve page?  Also at the moment I am using cyan as toner 1 and 
magenta as toner 2, at what point should I conclude that I should be 
using yellow as a toner rather than either the cyan or magenta?

Also what are the benefits of using 'copy curve from' for one of the 
colours as compared to defining it as a toner channel?

I understand that there will always be a certain amount of trial and 
error involved and that I will have to make a whole bunch of test 
prints but it would be nice to have some methodical approach rather 
than just randomly changing one variable at a time to see what effect 
it has.

As you can see I have a lot of basic questions on how to adjust the 
toning curves, so I am hoping that there might be something you can 
refer me to, as I realise it's a bit too much to expect anyone to 
answer them all.

Is there any rough methodology that should be followed when trying to 
adjust the warmness or coolness of a print, or something that 
describes what effects the various controls in QTR are designed to 
have?

Regards, Bill

--- In QuadtoneRIP@yahoogroups.com, "Roy Harrington" <roy@...> wrote:
>
> Bill,
> 
> There are a lot of profiles for the 3800/UC inks already in the 
download.  I'd
> first try these -- I think you'll find them at least a very good
> start.  If you really
> want to make some of your own, look at how the existing ones work.
> 
> Roy
> 
> On 10/19/07, etlblbt <bill.brandt@...> wrote:
> > Thanks to everyone who replied.  I have access to a microscope so 
I
> > took a part of the print and examined it visually at a 
magnification
> > where I can see the individual ink dots.  I can see that all the 
dots
> > are grey and there are no other colours being laid down so my only
> > conclusion is that the grey inks are not truly neutral and do 
have a
> > warm tone to them (or there is some tone coming from the paper).
> >
> > So now it looks like I am going to have to use the toning 
channels to
> > bring the print back to a true neutral.  Is there a good method 
for
> > establishing how to set the toning channels to achieve a neutral
> > print?  I have access to an eye-one.
> >
> > Bill
> >
> > --- In QuadtoneRIP@yahoogroups.com, "Michael King" <drmrking@>
> > wrote:
> > >
> > > Also what your spectro reads is going to depend on the colour of
> > the paper
> > > the inks are printed on.
> > >
> > > On 18/10/2007, Michael King <drmrking@> wrote:
> > > >
> > > > Isn't that because the blacks are not neutral. They are 
naturally
> > warm
> > > > carbon?
> > > >
> > > > Mike
> > > >
> > > >
> > > >  On 18/10/2007, etlblbt <bill.brandt@> wrote:
> > > > >
> > > > >   Hello,
> > > > > I have just started trying quadtone RIP and I have tried to 
make
> > > > > my first profile for my EPSON R2400 which is loaded with the
> > standard
> > > > > inkset. In the ink descriptor file I have set the density
> > values for
> > > > > the light black and light light black inks (measured using a
> > > > > spectrophotometer) and have set all the other inks to 'not
> > used'.
> > > > >
> > > > > When I print out a test strip (the 21x4 random) and analyse 
it
> > with my
> > > > > spectrophotometer I can see that the colours are not neutral
> > (when
> > > > > converted to RGB there is quite a lot less blue than the 
other
> > two
> > > > > channels) and the print visually has a brownish tone.
> > > > >
> > > > > Is there something else I need to do to prevent the colour 
inks
> > from
> > > > > being used other than setting them to 'not used' in the ink
> > descriptor
> > > > > file.
> > > > >
> > > > > Apologies if this is all in a FAQ somewhere. If you could 
point
> > me to
> > > > > it that would be great.
> > > > >
> > > > > Regards, Bill Brandt
> > > > >
> > > > >
> > > > >
> > > >
> > > >
> > >
> > >
> > > [Non-text portions of this message have been removed]
> > >
> >
> >
> >
> >
> >
> > Yahoo! Groups Links
> >
> >
> >
> >
>