>
> The idea came from the way I decided to go about creating my basic
> curves. Firstly, the Carbon curve at 1 extreme and the Cool curve at
> the other extreme, so in my mind by using the blending option in QTR
> I should theoretically move up and down the Lab B axis (give or take)
> and then if I spend time producing the best standalone neutral curve
> that I can for my setup, I should in theory, be able to move along
> the Lab a axis from a roughly neutral position to where ever I
> wanted to go (obviously image dependant) using the Lab a axis toner
> curve. Maybe my thinking is to simplistic and someone could jump in
> with a few ideas,
>
> Jamie.
>
Jamie and Joost,
I've followed this correpondence and thought now would be the time to
jump in. Like Jamie, I'm playing with UT-3D inks in a 1290 and have
recently started using QTR. Like both of you, I've felt that
mixing 'standard' curves was the way to go for producing a full range
of tones. I've implemented this approach - kind of - in photoshop, and
am working on it for QTR also.
I've spent quite a bit of time in the last few weeks developing
Photoshop curves for this inkset, and have generally been pleased with
the results. Although it's quite fiddly and time-consuming (especially
as I'm using a flatbed scanner to read the test strips) I've been able
to produce pretty much exactly what I've wanted, at least within the
accuracy of the scanner and the gamut of the inks. The approach I've
taken has been a little different to what I understand the two of you
have done, in that I've aimed for starting curves that sit on the a-
and b- axes as far as possible. I found that printing 'fully cold'
produced a noticable greenish cast in some tones, so my 'cold' curve
has some a-axis toner in it. Similarly, my neutral curve is tweaked to
come as close as I can get it to pure grey.
It seems that the gamut of the inkset makes an on-axis curve harder to
achieve in the warm tones, although I did manage to produce a very
slightly warm (lab b around +2)curve with lab a around 0 in the
midtones and highlights. (I was really more interested in getting the
green out of the cool tones, as I quite like the natural carbon tone).
I've had some success 'interpolating' between my neutral, cool, warm
and carbon curves by blending in Photoshop. To do this I applied the
curves to separate copies of the image, flattened each and overlaid
them with opacity between 0 and 100%. This seems to produce broadly
what I was after (I linearised my original curves 'the hard way') but
I'm sure creating a new ICC for the blend would do a better job.
I didn't follow this any further because the limitations of the Epson
driver were becoming apparent, with horizontal banding evident in
spite of my best alignment efforts and no way to print at 2880 on
heavyweight matte paper. So I dived into QTR.
At this point, I'm just getting started, but I've had a look at
Joost's curves and re-linearised the carbon one for my printer, just
for fun. I then made a pure carbon curve from scratch, mostly as a
learning exercise but also to form a view on the relative densities
and best ink limits for the carbon inks for this printer. So far so
good.
My intention is to follow the same approach as I used with Photoshop -
I'm working on a neutral curve at present. I'm keen to get into the +a
tones also. A thought I had looking at Joost's 'selenium' curve: the
Eboni ink seems to have a natural +a / -b tone, with suggests to me
that an approach with just Eboni, a-axis toner and one or both Carbons
to bridge the density difference, could be worth trying. I'll let you
know how I get on with it - unless someone else has been there first!
I hope at least some of that is interesting and/or useful. My PS
curves are available to anyone who wants them, and I look forward to
further developments.
All the best,
Ben Connor