Digital BW, The Print

Susan,

I will attempt the most simple explanation:

(1) The whitest that can be achieved in a print is bare paper; where there is no ink at all. This is known as "paper white"
(2) The darkest that any paper/ink combination can achive is "maximum density" also commonly called "Dmax".
(3) Density is a measure of how dark dark something is. Density can be measured by any number of instruments.
(4) You now have "paper white" and "Dmax" at the two extreme ends of the density range.
(5) When you print, you want to make sure that the grays between these two end are well-behaved. The image in Photoshop will have pixels going from the brightest to the darkest. This progression of brightness to darkness in the image file should be accurately (linearly) represented in the print you make. When you have achived that, you have essentially a "linear" work flow.

So why do we have to linearize? To get to this requires a little complex understanding, but not very complex.

(6) Most inkjet papers have a density of paper white close to zero (range of 0.02 to 0.06 is common; almost zero for most purposes)
(7) Dmax is dependent much more strongly on the paper AND the ink. I am sure you know that glossy type (glossy, luster, etc papers that use PK ink) have much greater "blackness" or Dmax than matte papers that use MK inks.
(8) Suppose you have a pure gray file in Photoshop, somewhere between pure white and pure black (say 50%). Now you print this file on 2 different papers through identical printer settings. If you then measure the print densities on these papers, it is common that the measurement will be different. So what's up with that? Well, as I said earlier that Dmax is dependent on the paper/ink combo. The same is true of ALL densities greater than zero. Each paper reacts differently to ink being layed down on it, and shows different densities.
(8) When you use Epson papers, on Epson printer, Epson ink, Epson driver, the variability paper-to-paper has been taken care of in the paper selection. If you use a third party paper, all bets are off. There is no guarantee that this paper will behave (linear) the same as the equivalent Epson paper.
(9) Hence the need to linearize for each paper.
(10) To make matters more difficult (not more complex, just more difficult), even the same ink and paper could have batch-to-batch variability, requiring tweaks to "linearization."

Does this make sense? Please ask if you need more information, or need any clarification. As you can imagine, I have only skimmed the surface. The rest as they say "the devil is in the details." It is really not that difficult to grasp, but you have go about it in small steps.

As a teaser: you can two different papers, each with identical paper white and Dmax, but each will still require unique linearizing. Think about that. That is when things get interesting.

Regards.

Shilesh

--- In DigitalBlackandWhiteThePrint@yahoogroups.com, "slcphoto73" <slchapin41@...> wrote:
>
> I've asked, and asked, also in the QTR forum and I don't know how many other places, but no one answers a simple question - what do you mean by "linearize"? - in a simple way. 
> 
> Thank you all for the how-to references and I will read them, but could you get me started by providing a dictionary definition of "linearize"? Not a how-to, just a dictionary definition.
> 
> Thanks,
> 
>   - susan
> 
> --- In DigitalBlackandWhiteThePrint@yahoogroups.com, Michael King <drmrking@> wrote:
> >
> > So firstly you are better off asking straight QTR questions over on the QTR
> > forum.... more people to help you and if you follow that forum postings you
> > will learn a lot about QTR.
> > 
> > Secondly there is actually quite a lot of info around for example
> > http://www.diallophotography.com/pdfs/QTRworkflow.pdf
> > 
> > And Paul Roark's web site has tons of info as well.
> > 
> > The standard QTR tutorial while dated, is also still relevant.
> > 
> > Yes there is a terminology learning curve, but all the info is actually
> > available in one place or another for the next step up the ladder - making
> > QTR curves with QTR.
> > 
> > Mike
> > 
> > On 1 May 2010 16:31, Paul <paulmwhiting@> wrote:
> > 
> > >
> > >
> > > Susan,
> > >
> > > I agree. I wish there were some of tutorial and/or glossary available here.
> > > I've looked at the Files menu here but it's rather sparse and a bit dated.
> > > I've stuck to using a very basic setup for now... 3 black cartridges (using
> > > Eboni ink by MIS), QTR with the profiles Paul has developed, and one or two
> > > papers. Works well for me... but I probably should branch out some day.
> > >
> > > Paul
> > >
> > > > Oh, please, does this finally answer a question I have had for a long
> > > time that keeps me from wanting to use QTR -- *** does "linearize" mean the
> > > same thing as "create your own profile using MeasureTool and Create_icc.exe"
> > > *** ????? If not, what does it mean?
> > > >
> > > > I find the available documentation for QTR, once you want to go beyond
> > > using built-in curves, rather impenetrable; undefined terms are part of the
> > > problem.
> > > >
> > > > Thank you,
> > > >
> > > > - susan
> > > >
> > >
> > >  
> > >
> > 
> > 
> > [Non-text portions of this message have been removed]
> >
>