Digital BW, The Print

Austin,

InkjetControl allows you to type in the printed densities of a 26-patch target 
that it generates internally. It then plots the results and compares them to a 
plot of a set of ideal densities (so-called "aims") based on the dmin / dmax 
numbers you provide.  You can see the 2 curves plotted within the 
"linearization" tab.

At that point you have a choice: you can either tweak  the curves that control 
how much ink each nozzle puts down, then reprint the target and read it in 
again and again until you are satisfied. 

Or.... amazingly you can let the software do it for you! It will internally compare 
your printed densities to the Aims it generates for them, and adjust the output 
(without physically changing the ink curves you created, but rather by putting 
a correction stage "after" they are applied).

Which of the two approaches you choose depends on a number of factors, but 
the point is you have that option. One of the uses of the densitometer, then, is 
to "linearize" an existing profile for the particular  conditions of the day. As a 
result you can produce the exact same densities day to day, year to year, 
printer to printer and paper to paper (within the variances of the density range 
allowed by a given system).

The other important benefit of using an Aims-based system (whether you use 
the auto-linearization featue or not) is that it gives you the chance to distribute 
your print densities across the full density range (DR) that your system is 
capable of.  It also frees ink manufacturers from having to match their ink 
densities to those old  canned profiles of yesteryear. 

For example, if your maximum density is 1.8 on a 0.04 paper white,  the Aims 
will distribute this whole range across the 26 steps. If you are only capable of 
1.6 on a 0.06 paper, the Aims will again redistribute that range evenly across 
the whole of the 26 steps. This is a distinctly different approach from just using 
an old canned profile with a new black ink that produces a deeper black.

The downside of all this is that, while the Aims approach a gamma 1.8, they 
don't quite match it in the shadows (they are more open than 1.8). As a result, 
for accurate preview on a calibrated monitor, you still have to create a dot gain 
curve and use the soft proof feature to preview the print (without matching the 
ink color of course). 

As an aside, the Printmaker part of the software (it comes as 2 separate 
applications) gives you a choice of a print gamma 1.8 or 2.2  but I don't think 
this necessarily means it matches a gamma standard as understood in 
Photoshop etc. Currently the program does not recognize or report embedded 
gammas. 

And just for kicks - and adventurous souls - you can entirely bypass the 
built-in  aims and linearization and create your own "ideal" density curve in 
Excel, then use the ink controls of IJC to match it.  Of course, you then have to 
resort to trial-and error (print the 26-step  target, read it, plot it in Excel, tweak 
the inks and reprint). In practice, however, it doesn't take that many rounds to 
bring a profile  to within +-0.02 of whatever curve you desire. How's that for 
open-ended customization? It brings unprecedented digital-to-analog control 
to bw printmaking.

Hope this helps explain the relevance of the densitometer...

Antonis


> I don't know how it relates though to your inkjet control printmaking
> software...
> 
> Regards,
> 
> Austin