Digital BW, The Print

Steve,

I hope we are talking same apples and apples. If we were to linearize the process to 1.0 
Gamma, it would be scientifically linear - but humans would see it as "flat". The reason we 
choose to linearize PiezographyBW ICC and iQuads to a Gamma of 1.8, was that we wanted 
a system which would behave the same from printer group to printer group. In other 
words, the output of an 1160 would closely replicate the output of a 7000. Now the end 
points may be different. dMax in one may be greater than the other (and no one would 
want to cut back on dMax!) But when printed - would the same image have about the 
same relative contrast from printer to printer? And could that contrast be very very similar 
between printer families. So that is Gamma in an inkjet useful way, and we bring Gamma 
into our linearization process. Perhaps that is where our process differs.

On the initial Beta of K7 we did not linearize with our intended Gamma - and as we 
suspected we had a range of comments about the output in relation to either highlights 
(mostly) and to some shadows.

So part of our final process is to linearize the process so that there are nice even steps 
between the grays. But as I mentioned, if we make that linearization 1.0 - no one is going 
to "see" it as a visually logical progression from light to dark. Humans prefer contrast. So 
which contrast? If we darken and lighten the near-to-the-ends to create a contrast - we 
need to specify one. We choose Gamma 1.8 for several reasons.

So a Gamma is applied in our linearization process that makes sense to the average 
human eye. Another way to think of Gamma of course, is as a compensation for the 
human visual system.  Linearization on its own may not always make the best visual sense 
- unless you linearize to a system of tone that a human responds. I can't apparently 
emphasize Gamma enough when talking about linearization. Sometimes scientists when 
they begin producing drivers and the like for humans - forget all about the human 
condition, or worse yet they are unaware completely of the human condition. They then 
tend to make tools which are not consistent from printer to printer, but satisfy their own 
scientific process. EPSON too, obviously has computer scientists making their printer 
drivers and not artists or psychologists. There are other creators of software too that have 
complete disregard for the human condition - and yet humans are the intended target 
audience. The problem here is that inkjet printing is now so very much about photography 
and image interpretation - whereas earlier in its infancy it was about scientific 
visualization and graphics. 

We built a software to enable this process in-house (relating output to how humans see). 
So we're supplying our own curves to Roy for his QuadTone RIP. But a user can make their 
own with his process as you know. We think our supplied final curves will be best. 
However, not everyone will agree. So they can be tweaked and or replaced. I suppose we 
could make custom curves for users - do not know if we will go down that road though.

Why not Gamma 2.2 you say? or you might say next!! :)  I believe that humans respond 
better to a Gamma of 1.8.  And any Mac or PC can be calibrated to 1.8. Just preference.

best,

Jon Cone



--- In DigitalBlackandWhiteThePrint@yahoogroups.com, Steve Kale <stevekale@b...> 
wrote:
> Jon
> 
> Can I pick up on your comment below and one which you made in an earlier
> post "we are playing with the final curves for QuadTone Rip to get some more
> out of the highlights and shadows - and produce a Gamma 1.8 for previewing."
> This to me sounds like fine tuning the linearization process.  Can you
> explain a little bit more?
> 
> We have grappled with this issue a lot on this forum, particularly in
> relation to matte papers.  Linearizing L* when making curves produces a
> distinctly different gamma than 2.2 which many are using as their workspace,
> and the print gamma will change depending on the dMax and dMin end-points.
> This is the old "why are my prints 'flat' and 'lighter' (even in the mid
> tones) than on screen issue" when using a linearized Same as Source
> workflow.  The issue persists with the new Epson K3 driver.  The Epson
> driver and a 4800 produces a greyscale whose L* ramp is very linear.  Couple
> this with dMax of, say, L*=15 on matte and you get every tone from about 85%
> white printing "lighter than it should" when no colour management is in
> place (a la Adv B&W).  Apparent (and actual) contrast falls and prints look
> flat out of the box.  (It's much less of an issue on the photo papers
> because dMax L* is down at 3.3ish and the shift is much less pronounced.)
> 
> If I am right, you are driving at the heart of this issue and since you
> clearly have enormous knowledge some input from you would be very much
> appreciated.  
> 
> [Roy tackled this issue by profiling the luminance "shape" of the print
> space with a greyscale ICC profile and consequently gaining access to CMM
> technology to manage the transition. The CMM manages the greyscale luminance
> axis (and the hue of the curve is managed by the curve designer as before).]
> 
> Steve
> 
> 
> > From: piezobw <piezobw@c...>
> 
> > 
> > I don't think there is any doubt though that additional dilutions increases
> > fidelity, as long
> > as its handled properly by software or driver.
> >