QTR-Quadtone RIP

Hi Carl,

It's easy to do on the Mac, too.     Just use:
CURVE_K=k7_black.acv
CURVE_LM=k7_ltmagenta.acv
etc...

Howard's idea is an interesting possibility.   You could design the 
basic curve
shapes this way and then linearize the result.   The potential 
difficulty would be
that you get some flat spots or extra wiggles in the density curve.   
Just because
the look smooth doesn't mean the sum on the curves with different inks 
would
also look that smooth.  The linearize can fix only so much.   In the 
specific example
it probably would work well since they are designed from existing 
"good" profiles.

Since the K7 inks are so close in density you can have the very large 
overlaps
-- ie. 5 inks instead of just 3.   There is also some benefit in the 
2880dpi because its
only one dotsize.   At 1440 there will be 2 or 3 dotsizes used which 
results in more
transitions.

For anyone wanting to customize their own K7 ink profiles a very nice 
approach is
to take advantage of the piezo k7 profiles and then build ICC profiles 
on top of
them.  This way you get full color management from screen to print with 
softproofing
as well.

Roy

On Tuesday, January 16, 2007, at 03:14  PM, Carl Schofield wrote:

> I assume this is only for the PC version or is there a way to use
> the .acv curves with the Mac version of QTR?
>
> Carl
>
> On Jan 16, 2007, at 5:44 PM, Howard Shaw wrote:
>
>> Joost
>>
>> If you have a look at the Cone-made k7 curves (the 2880dpi ones) they
>> are differently constructed to the type of curves that qtr makes.
>>
>> I've made a web page showing the difference and also how the Load
>> curves
>> facility in qtr can be used to emulate the type of curves produced by
>> Cone's proprietary method.
>>
>> http://www.howardshaw.org/docs/k7-qtr/k7curves.htm
>>
>> The main difference is that the normal qtr curve creation method using
>> density boundaries usually only allows 3 inks to overlap at a time
>> whereas the Cone curves have upto 5 overlapping inks. On the basis
>> that
>> the more jets firing the better this should lead to a smoother print.
>>
>> Note that I do not have the K7 inks so this is a technical exercise
>> only.
>>
>> Howard
>>
>> Joost Horsten wrote:
>>> --- In QuadtoneRIP@yahoogroups.com, "Scott Schroeder" <schrochem@...>
>>> wrote:
>>>
>>>> I didn't mean you couldn't make curves. I was just saying you can't
>>>> make curves that have the nice transitions and crossovers that are
>>> in
>>>> the supplied curves.
>>>> This message will explain it better:
>>>> http://tech.groups.yahoo.com/group/QuadtoneRIP/message/1165
>>>
>>> Thanks Scott, that explains your remarks indeed. But for my
>>> information: does it make in practice REALLY any difference whether
>>> you use these original PiezoBW curves in stead of making your own
>>> curves with QTR? Since I'm printing on 2880 dpi with QTR/2100/UT3D
>>> I've a hard time to find any grain in my prints. So, imho on that
>>> aspect I expect there is little left to improve by going to 7 inks.
>>> But even if so, do the details of the curve then still make a
>>> difference on top of that? Or does the claimed smoothness of the NK7
>>> inks ONLY appear with the custom PiezoBW curves?
>>>
>>>  Joost
>>>
>
>
-
Roy Harrington
roy@...
Black & White Photo Gallery
http://www.harrington.com