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How Many Shades of Gray - K7 vs K3?

How Many Shades of Gray - K7 vs K3?

2011-03-19 by shileshjani

I just read an interesting post by Jon Cone here:

http://www.piezography.com/PiezoPress/blog/piezography-technical/making-a-fine-piezography-print/

He says on page 2 of the pdf:

"Because Piezography with four or as many as seven distinct shades of ink can separate more tonal values than can the OEM three shade systems, it is important to start with very smooth image files that have a long tonal scale. Without going into mathematics and the virtues of using overlapping shades of Piezography inks rather than the interlinking shades of the OEM, the Piezography system produces tens of thousands more gray value combinations than can the OEM"

Is this true? When I arbitrarily open up a QTR curve for K7 inks published by Piezography, I find exactly 256 gray values, for each there is an assignment of inks to be used. But 256 (8 bit) gray values, no more no less.

To be provocatine, I say even a single black only (BO) system can print 256 shades gray. To be fair, the multiple ink set-up of K7 (or K3 for that matter) will produce each of the 256 shades with greater smoothness and overall finess than a BO print. Using the 8 bit QTR set-up, both BO and multi K will each produce 256 shades of gray.

I think some people do not realize that if your image is 8 bit, there are 256 shades available, and no interpolation between them is allowed. Even if the ink/paper system is capable of producing more shades than 256, it is never achieved in reality. The same applies even if your image is 16 bits, because QTR curves are described in 8 bit architecture.

In summary, on one single paper, K7, K3, or BO all produce AT MOST 256 shades of gray. It can be argued that using ABW on that same paper, you can actually produce many, many more shades of "near-neutral gray", but only 256 at a time. Again, ABW gets maligned in a manner that has no basis in fact.

Did I get this all wrong? Is there something to this that eludes my mind? Or is the ".........tens of thousands more gray value ....." just poetic waxing?

I concede there are some reasons to chose multi K systems like Piezography K7, but greater number of gray shades?

Shilesh

Re: [Digital BW] How Many Shades of Gray - K7 vs K3?

2011-03-19 by Michael King

Shilesh,

So let me dissect Jon's statement ...

"Because Piezography with four or as many as seven distinct shades of ink
can separate more tonal values than can the OEM three shade systems"

This is true in principle as more ink curves potentially increase the
overall tonal palette.

" it is important to start with very smooth image files"

Not sure how this is any more relevant to K4-7,  as even a single QTR ink
curve picks from a palette of 65536 tones.

"that have a long tonal scale."

In practice K7 prints tend to have very good shadow separation. But that's
because of better profiles and workflow than anything else.

"Without going into mathematics and the virtues of using overlapping shades
of Piezography inks rather than the interlinking shades of the OEM, the
Piezography system produces tens of thousands more gray value combinations
than can the OEM"

This is potentially true. More overlapping curves mean more gray value
combinations i.e. larger palette to draw from. But given that a single QTR
channel draws from a palette of 65536 tones you have to wonder what value a
bigger palette brings.

To be honest IMO the real value of more overlapping ink curves is that you
have more heads in play. As we see in many situations more heads means
smoother tonal transitions and less risk of posterization.

So in summary is K7 smoother than K3 - yes when it matters, has it got
anything to do with their being more tones, probably not. Its almost
certainly due to the fact that more inks mean more heads in play.

Mike



On 19 March 2011 04:52, shileshjani <janishilesh@...> wrote:

>
>
> I just read an interesting post by Jon Cone here:
>
>
> http://www.piezography.com/PiezoPress/blog/piezography-technical/making-a-fine-piezography-print/
>
> He says on page 2 of the pdf:
>
> "Because Piezography with four or as many as seven distinct shades of ink
> can separate more tonal values than can the OEM three shade systems, it is
> important to start with very smooth image files that have a long tonal
> scale. Without going into mathematics and the virtues of using overlapping
> shades of Piezography inks rather than the interlinking shades of the OEM,
> the Piezography system produces tens of thousands more gray value
> combinations than can the OEM"
>
> Is this true? When I arbitrarily open up a QTR curve for K7 inks published
> by Piezography, I find exactly 256 gray values, for each there is an
> assignment of inks to be used. But 256 (8 bit) gray values, no more no less.
>
> To be provocatine, I say even a single black only (BO) system can print 256
> shades gray. To be fair, the multiple ink set-up of K7 (or K3 for that
> matter) will produce each of the 256 shades with greater smoothness and
> overall finess than a BO print. Using the 8 bit QTR set-up, both BO and
> multi K will each produce 256 shades of gray.
>
> I think some people do not realize that if your image is 8 bit, there are
> 256 shades available, and no interpolation between them is allowed. Even if
> the ink/paper system is capable of producing more shades than 256, it is
> never achieved in reality. The same applies even if your image is 16 bits,
> because QTR curves are described in 8 bit architecture.
>
> In summary, on one single paper, K7, K3, or BO all produce AT MOST 256
> shades of gray. It can be argued that using ABW on that same paper, you can
> actually produce many, many more shades of "near-neutral gray", but only 256
> at a time. Again, ABW gets maligned in a manner that has no basis in fact.
>
> Did I get this all wrong? Is there something to this that eludes my mind?
> Or is the ".........tens of thousands more gray value ....." just poetic
> waxing?
>
> I concede there are some reasons to chose multi K systems like Piezography
> K7, but greater number of gray shades?
>
> Shilesh
>
>  
>


[Non-text portions of this message have been removed]

Re: [Digital BW] How Many Shades of Gray - K7 vs K3?

2011-03-19 by Mark

Yes, I agree with Michael. It's not really about absolute levels of tone differentiation, it's about high frequency modulation of details (which translates into tonal smoothness of fine details). Consider a billboard sign comprised of a checkerboard pattern with an ordered array of one square inch black squares and one square inch white squares. If you stand far enough away from the billboard, your eyes can't resolve the pattern. You will see a smooth light gray tonal pattern across the whole billboard (approximately 50% average reflection = about 0.3 density or a lab L* value = 76). As you move closer to the sign, you will begin to perceive slight pattern noise and thus a slight bifurcation of tone, ie. two tones with one tone slightly lighter and the other slightly darker, but you still won't resolve the black and white squares. Now move closer still, then you will finally begin to resolve the black and white squares. This is analogous to what is happening with 3 dots of gray inks versus 7, only unlike the two tone sign example you now have 4 tones to play with in the pattern for the 3 gray ink set (i.e, you have paper white as the fourth tone) or 8 tones to play with in the 7 ink system (again, with a paper white/no ink dot tone which makes eight levels of tone per dot location).  So smoothness and detail does increase with more tone levels per dot placement value on paper.  It allows the viewer to inspect the print closer and closer and still see what appears to be continuous tonality.

Does the average viewer get so close to see the dot pattern noise generated by the latest inkjet printers? No, but to the very discerning viewer, there is still a tangible difference, sort of like looking at contact prints made in the darkroom versus optically enlarged prints. As enlargement factors go up, tonality and sharpness starts to break down into grain pattern noise at a specific viewing distance from the print, and the resolving power of the human eye then starts to exceed the resolved features in the image.

Re: [Digital BW] How Many Shades of Gray - K7 vs K3?

2011-03-19 by shileshjani

OK Mark & Michael, what you write makes sense, in priciple at least. From a practical stand point, let us focus on what you write below about silver contact prints.

Tyler Boley published this quite a while back.

http://www.custom-digital.com/2008/09/bw-print-quality/

Looking at the last image where there is a direct comparison of ABW and K7, each printed at 2880 dpi, and contrasted to silver contact print. Frankly, if this level of viewing magnification is realistic, even K7 is abysmal compared to silver contact. I mean really bad. I can step 10 feet away from my monitor and discern difference (smoothness) between silver contact and the inkjet prints. At 10 feet, other then the color differences, I don't see any objective difference among the inkjet prints.

So, for a while I have been of the opinion (biased, no doubt) that if the very best (K7 for smmothness) inkjet is acceptable in comparison to a contact print, then ABW K3 is equally acceptable. So workflow choices can be made on considerations other than smoothness, where clearly K6/K7 reign (at least microscopically).

Shilesh


--- In DigitalBlackandWhiteThePrint@yahoogroups.com, "Mark" <mark@...> wrote:
>
...SNIP......
 
> Does the average viewer get so close to see the dot pattern noise generated by the latest inkjet printers? No, but to the very discerning viewer, there is still a tangible difference, sort of like looking at contact prints made in the darkroom versus optically enlarged prints. As enlargement factors go up, tonality and sharpness starts to break down into grain pattern noise at a specific viewing distance from the print, and the resolving power of the human eye then starts to exceed the resolved features in the image.
>

Re: [Digital BW] How Many Shades of Gray - K7 vs K3?

2011-03-19 by Paul

"shileshjani" <janishilesh@...> wrote:
>
> ...let us focus on what you write below about silver contact prints.
> 
> Tyler Boley published this quite a while back.
> 
> http://www.custom-digital.com/2008/09/bw-print-quality/
> ...

Contact prints are amazing, but comparing them to inkjet prints is a bit of an apples and oranges comparison.  If we look at enlargements to display sizes, the inkjet prints start to look much more competitive.

Paul
www.PaulRoark.com

Re: [Digital BW] How Many Shades of Gray - K7 vs K3?

2011-03-19 by wolarsky

Several years ago, Amadou Diallo invited members of this group attending Photo Expo to print a standard file using our various workflows and then get together in his studio to compare the results.About a dozen of us downloaded a large file that Amadou supplied and printed the "standard" print on Photo Rag. We also printed an interpretive version of the RAW file. 

Since I was an amateur using a plain vanilla Epson 2400 with ABW I showed up at his studio worried that I would somehow be laughed out of the room. Virtually all the attendees either ran professional printing studios or were Photoshop instructors. However, when we each tacked up our prints on his viewing wall, I found that I couldn't tell any difference between my standard print and the others. Thinking that perhaps my perceptual abilities were not up to the job, I asked several people around me to point out the differences. Even with our noses to the prints, no one seemed to be able to show me why any of the others was better. 

The point of my comments is not to deny that there is a difference between the inkets, but rather that the differences must be very small and perhaps insignificant for most of us. Certainly, the differences in our abilities to manipulate the digital files is of far greater importance to the final print than differences in the inks.

Evan

Re: [Digital BW] How Many Shades of Gray - K7 vs K3?

2011-03-19 by BKPhoto@aol.com

All-


I would clarify what I believe is an important point. It isn't just the inks that matter; although I find the aesthetic differences in inks to be very important.


It's controlling how those inks are used to make a print. In my experience there is no OEM printing workflow that can compare to a properly ink limited, linearized, and profiled workflow. You do no have access to this degree of control on the OEM path, including ABW.


For the record, I support the good intentions of those working on the OEM path. And believe that for many it will, properly used, produce a print they are content with. And, as Evan points out, if you cannot see a difference--or a difference that matters to you--it is a mute point.


But the differences do exist and they can be seen. If not in resolution, or tonal scale, then most obviously in the ability to produce a spectrally neutral grayscale print using color inks.




Bill Kennedy
Show quoted textHide quoted text
-----Original Message-----
From: wolarsky <wolarsky@...>
To: DigitalBlackandWhiteThePrint@yahoogroups.com
Sent: Sat, Mar 19, 2011 2:23 pm
Subject: Re: [Digital BW] How Many Shades of Gray - K7 vs K3?


  
    
                  


Several years ago, Amadou Diallo invited members of this group attending Photo Expo to print a standard file using our various workflows and then get together in his studio to compare the results.About a dozen of us downloaded a large file that Amadou supplied and printed the "standard" print on Photo Rag. We also printed an interpretive version of the RAW file. 

Since I was an amateur using a plain vanilla Epson 2400 with ABW I showed up at his studio worried that I would somehow be laughed out of the room. Virtually all the attendees either ran professional printing studios or were Photoshop instructors. However, when we each tacked up our prints on his viewing wall, I found that I couldn't tell any difference between my standard print and the others. Thinking that perhaps my perceptual abilities were not up to the job, I asked several people around me to point out the differences. Even with our noses to the prints, no one seemed to be able to show me why any of the others was better. 

The point of my comments is not to deny that there is a difference between the inkets, but rather that the differences must be very small and perhaps insignificant for most of us. Certainly, the differences in our abilities to manipulate the digital files is of far greater importance to the final print than differences in the inks.

Evan


    
             

  
 


[Non-text portions of this message have been removed]

Re: [Digital BW] How Many Shades of Gray - K7 vs K3?

2011-03-19 by piezobw

Hi Shilesh,

Perhaps you are too cerebral about all this. A little more than a year ago you contacted me to see samples of my process, you asked me for the spectral data rather than the printed examples themselves - and I obliged but felt that you should see your work in the process rather than see your image through a soft proof ICC. 

At the time I wrote "plotting Lab values is not the same as seeing the glow, the depth, the bits and pieces which separate systems from their spectral data."

Sometimes, in all of this interesting technology with all the bits (no pun intended), seeing is believing, rather than trying to sort it out in an intellectual manner. I don't think that you can ever resolve something aesthetic through reasoning.

However, the most important thing is that you're happy with the results you are producing. So, if you have doubts, if you think that they could be better, or if you think they are not as good as your analogue work was - then probably it isn't - and you should really look at the physical evidence of prints by comparison. I think looking at comparative prints is where eventually you will find the answers to whether your printing process is as strong as you want or as strong as you need.


I had offered to make you a print with my process online many moons ago when you asked for the spectral data. Perhaps you should try the MPS system directly. Here is the link again:

http://shopping.netsuite.com/s.nl/c.362672/sc.15/category.29284/.f

You upload your image after choosing the inks, paper, size - and we send you a print in a few days.

regards,

Jon


--- In DigitalBlackandWhiteThePrint@yahoogroups.com, "shileshjani" <janishilesh@...> wrote:
Show quoted textHide quoted text
>
> OK Mark & Michael, what you write makes sense, in priciple at least. From a practical stand point, let us focus on what you write below about silver contact prints.
> 
> Tyler Boley published this quite a while back.
> 
> http://www.custom-digital.com/2008/09/bw-print-quality/
> 
> Looking at the last image where there is a direct comparison of ABW and K7, each printed at 2880 dpi, and contrasted to silver contact print. Frankly, if this level of viewing magnification is realistic, even K7 is abysmal compared to silver contact. I mean really bad. I can step 10 feet away from my monitor and discern difference (smoothness) between silver contact and the inkjet prints. At 10 feet, other then the color differences, I don't see any objective difference among the inkjet prints.
> 
> So, for a while I have been of the opinion (biased, no doubt) that if the very best (K7 for smmothness) inkjet is acceptable in comparison to a contact print, then ABW K3 is equally acceptable. So workflow choices can be made on considerations other than smoothness, where clearly K6/K7 reign (at least microscopically).
> 
> Shilesh
> 
> 
> --- In DigitalBlackandWhiteThePrint@yahoogroups.com, "Mark" <mark@> wrote:
> >
> ...SNIP......
>  
> > Does the average viewer get so close to see the dot pattern noise generated by the latest inkjet printers? No, but to the very discerning viewer, there is still a tangible difference, sort of like looking at contact prints made in the darkroom versus optically enlarged prints. As enlargement factors go up, tonality and sharpness starts to break down into grain pattern noise at a specific viewing distance from the print, and the resolving power of the human eye then starts to exceed the resolved features in the image.
> >
>

Re: [Digital BW] How Many Shades of Gray - K7 vs K3?

2011-03-19 by shileshjani

Jon,

Yes indeed, the print-in-hand is the best way to judge. Therein is my difficulty; I have seen prints from many inks/paper combination. I am also sincere in my "am I missing something?" So I like to hear from others who have no axe to grind.

Lately due to woes with banding (perhaps another 3rd pary ink related - not yours?), I have entertained using Piezography Sepia inks that are equivalent in density to OEM LK annd LLK. You were kind enough to run a quick experiment to show that these shades were glossy compatible - thank you, I appreciate that. The reason I was retricting myself to only LL and LLK equivalents is that I really (I mean really) abhor the thought of losing control over print color. Hence I will always have LC and LM high gamut inks in my system. I can create a whole bunch of color and splits, and I am not beholden to tha vagaries of the paper for color. But I kept asking myself: "am I missing something? Perhaps K6 or K7 is a better option." During my search, I ran into your PDF, and went "Huh?"

Anyway, I agree there is a big difference between verbally describing print quality and seeing the print first-hand. It is next to impossible to accurately describe quality, let alone why the quality is achieved.

Shilesh


--- In DigitalBlackandWhiteThePrint@yahoogroups.com, "piezobw" <jon@...> wrote:
Show quoted textHide quoted text
>
> Hi Shilesh,
> 
> Perhaps you are too cerebral about all this. A little more than a year ago you contacted me to see samples of my process, you asked me for the spectral data rather than the printed examples themselves - and I obliged but felt that you should see your work in the process rather than see your image through a soft proof ICC. 
> 
> At the time I wrote "plotting Lab values is not the same as seeing the glow, the depth, the bits and pieces which separate systems from their spectral data."
> 
> Sometimes, in all of this interesting technology with all the bits (no pun intended), seeing is believing, rather than trying to sort it out in an intellectual manner. I don't think that you can ever resolve something aesthetic through reasoning.
> 
> However, the most important thing is that you're happy with the results you are producing. So, if you have doubts, if you think that they could be better, or if you think they are not as good as your analogue work was - then probably it isn't - and you should really look at the physical evidence of prints by comparison. I think looking at comparative prints is where eventually you will find the answers to whether your printing process is as strong as you want or as strong as you need.
> 
> 
> I had offered to make you a print with my process online many moons ago when you asked for the spectral data. Perhaps you should try the MPS system directly. Here is the link again:
> 
> http://shopping.netsuite.com/s.nl/c.362672/sc.15/category.29284/.f
> 
> You upload your image after choosing the inks, paper, size - and we send you a print in a few days.
> 
> regards,
> 
> Jon
> 
> 
> --- In DigitalBlackandWhiteThePrint@yahoogroups.com, "shileshjani" <janishilesh@> wrote:
> >
> > OK Mark & Michael, what you write makes sense, in priciple at least. From a practical stand point, let us focus on what you write below about silver contact prints.
> > 
> > Tyler Boley published this quite a while back.
> > 
> > http://www.custom-digital.com/2008/09/bw-print-quality/
> > 
> > Looking at the last image where there is a direct comparison of ABW and K7, each printed at 2880 dpi, and contrasted to silver contact print. Frankly, if this level of viewing magnification is realistic, even K7 is abysmal compared to silver contact. I mean really bad. I can step 10 feet away from my monitor and discern difference (smoothness) between silver contact and the inkjet prints. At 10 feet, other then the color differences, I don't see any objective difference among the inkjet prints.
> > 
> > So, for a while I have been of the opinion (biased, no doubt) that if the very best (K7 for smmothness) inkjet is acceptable in comparison to a contact print, then ABW K3 is equally acceptable. So workflow choices can be made on considerations other than smoothness, where clearly K6/K7 reign (at least microscopically).
> > 
> > Shilesh
> > 
> > 
> > --- In DigitalBlackandWhiteThePrint@yahoogroups.com, "Mark" <mark@> wrote:
> > >
> > ...SNIP......
> >  
> > > Does the average viewer get so close to see the dot pattern noise generated by the latest inkjet printers? No, but to the very discerning viewer, there is still a tangible difference, sort of like looking at contact prints made in the darkroom versus optically enlarged prints. As enlargement factors go up, tonality and sharpness starts to break down into grain pattern noise at a specific viewing distance from the print, and the resolving power of the human eye then starts to exceed the resolved features in the image.
> > >
> >
>

Re: [Digital BW] How Many Shades of Gray - K7 vs K3?

2011-03-19 by Walker Blackwell

When dealing with the classic print quality question I like to remember that there are so many variables involved that there is no one part that is a deal-breaker. I've seen absolutely stunning prints from OEM inks. The trick with OEM is to control the inks they way you want to and not through their defaults if that does not work for you.

Why I've run more than 3 K inks over the last several years.  

1. A decrease in color shifts and metamerism. (And yes, even 9900 oem prints shift under different light more than quad K whatever Epson wants to brag about their deltas)
2. Faithful grain reproduction. (when printing a 16x20 from a 35mm you can actually see film grain just like a silver print. Epson ABW doesn't always get their with 400-3200 speed films.)
3. Tonal reproduction. (This one is always tricky. And I would say with the newest x900 printers and OEM ink, tonal reproduction is better than Quads. With 4x5 and smaller films printed 30x40 or larger, tonal reproduction is equiv to K7. However, sometimes you're looking for a very specific tonal feel. And sometimes quad or k3 is the way to go. It's like how all the sound techs are coveting the 16bit audio converters from the first ADAT machines even though we are at 24 and 32 bits now.)
4. Lastly is sharpness. Sharpness is a real hum-dinger because with over-inking it goes all to crap. And certain papers are less sharp with any inkset than say Portfolio rag with 4800 OEM. I've noticed that some printers don't perform very well with K7 and epson dithers no matter the limiting. The sharpest dot and detail I've ever seen personally has come from a 9600 through Studioprint using a Smooth Diffusion dither, K7 ink, and Portfolio Rag paper. They were drum-scans from 8x10 portraits taken close-up. Held against the 8x10 contact prints I could not see a difference in detail until I held a loupe to the prints. Tested on OEM 4800 with the same paper (to see a split hue) I could see a difference in detail clearly.

But in the end, it's up to the artist and the viewer and printer/ink/paper be damned! My fellow Columbia College student Curtis Mann bleaches cprints and it works! I have a student in our art department at UVM who is experimenting with chemical toning of inkjet prints. I want to start experimenting with 1 white channel and 3 K channels printing onto 18% gray!  The material and technical possibilities are endless in the digital world. Let us not forget that a drum-scan is still worlds beyond what a contact print can reproduce so our future resolution (in the 1-1 perspective)  will someday surpass that of silver.

Walker

[Non-text portions of this message have been removed]

Re: [Digital BW] How Many Shades of Gray - K7 vs K3?

2011-03-19 by CorrPro96@aol.com

In a message dated 3/19/2011 4:07:54 P.M. Eastern Daylight Time,  
wolarsky@... writes:

Several  years ago, Amadou Diallo invited members of this group attending 
Photo Expo to  print a standard file using our various workflows and then get 
together in his  studio to compare the results.About a dozen of us 
downloaded a large file that  Amadou supplied and printed the "standard" print on 
Photo Rag. We also printed  an interpretive version of the RAW file. 

Since I was an amateur using  a plain vanilla Epson 2400 with ABW I showed 
up at his studio worried that I  would somehow be laughed out of the room. 
Virtually all the attendees either  ran professional printing studios or were 
Photoshop instructors. However, when  we each tacked up our prints on his 
viewing wall, I found that I couldn't tell  any difference between my 
standard print and the others. Thinking that perhaps  my perceptual abilities were 
not up to the job, I asked several people around  me to point out the 
differences. Even with our noses to the prints, no one  seemed to be able to show 
me why any of the others was better. 

The  point of my comments is not to deny that there is a difference between 
the  inkets, but rather that the differences must be very small and perhaps 
 insignificant for most of us. Certainly, the differences in our abilities 
to  manipulate the digital files is of far greater importance to the final 
print  than differences in the inks.

Evan






Hi Evan:
I will echo this, as I was surprised at the quality of Evan's ABW version  
of the image, compared to the rest.... mostly versions of piezotone (from a  
1280 in my case), and various piezography inksets. One, perhaps important  
factor, was that the image Amadou had us print, had a narrow range of 
tones...  that is to say, flat. It was a photograph of a Dongon structure in the 
Sahara.  Outstanding, was Tyler Boley's StudioPrint version printed with his 
"secret  sauce" ink limiting.
 
Rich
_www.rmassiephotography.com_ (http://www.rmassiephotography.com) 
 
 


[Non-text portions of this message have been removed]

Re: How Many Shades of Gray - K7 vs K3?

2011-03-21 by Roy

Hi Shilesh,

Sorry but I have to disagree with this -- especially: QTR curves are 16-bit not 8-bit.   
Yes there are 256 points but each one is a 16-bit value.
> I think some people do not realize that if your image is 8 bit, there are 256 shades available,
> and no interpolation between them is allowed. Even if the ink/paper system is capable of 
> producing more shades than 256, it is never achieved in reality. The same applies even if 
> your image is 16 bits, because QTR curves are described in 8 bit architecture.
> 

I think the issue of 256 levels of gray is a misleading concept.  There are all these
parts of the process that have specs of 8-bit or 256 values that it is very easy to fall 
into the trap that the result print has to have 256 levels of gray.  But in real prints -- both
digital and film -- the perception of gray is always an average of lots of pixels in the
source and well as lots of dots of ink.   It's this averaging that fills in all the mid-grays
between each of the 256 grays -- essentially making a continuous print.  

On a print I can pretty easily see the difference between steps that are 1 unit apart
in 256 grays and 16-bit gradient across those same values.  (3800, K3 OEM inks & QTR)

So whether you are using K7, K3, or BO you will get more than 256 grays.  The difference
is mainly seeing dots in the BO case -- the dark black dots on white paper have
enough contrast that you see them with the naked eye.   I think the K3 LLK ink is
light enough that you don't see them -- and I mean get up close and look critically.
Most of my prints come from 4x5 film, tmax 100 and the grain from the film is more
obvious than the grain from the dots.   The K7 light inks are lighter still and can
stand more magnification before seeing the dots.   Tyler's article illustrates this,
but the main thing I get from his scans is the dot resolution of the print is the most
important factor -- 2880dpi is better than 1440dpi, and the silver dpi is still much
better than that.

The things I think are important are using 16-bit for all editing from 16-bit scan
or raw digital.  Use all the resolution you can.  QTR will use up to 720ppi, the
Epson driver with use this on most printers if you select Finest Detail.
To get great prints most things boil down to starting with the best image and
knowing now to edit and get what you want it to look like.

---------------

As far as what inks to use -- they are all good but there are tradeoffs and different
amounts of work to get there.   Probably the biggest aesthetic decision is matte
versus photo paper -- and within each category there are lots of choices.

K7 is great in that most is fixed and done for you.  K3 is great in that you have
fine tuning control of color tone including split tones if you use QTR.  Glossy
papers are often problematic and need GLOP but I find Harman Gloss Baryta
does really well with Epson K3 inks straight as is.

Roy

--- In DigitalBlackandWhiteThePrint@yahoogroups.com, "shileshjani" <janishilesh@...> wrote:
Show quoted textHide quoted text
>
> I just read an interesting post by Jon Cone here:
> 
> http://www.piezography.com/PiezoPress/blog/piezography-technical/making-a-fine-piezography-print/
> 
> He says on page 2 of the pdf:
> 
> "Because Piezography with four or as many as seven distinct shades of ink can separate more tonal values than can the OEM three shade systems, it is important to start with very smooth image files that have a long tonal scale. Without going into mathematics and the virtues of using overlapping shades of Piezography inks rather than the interlinking shades of the OEM, the Piezography system produces tens of thousands more gray value combinations than can the OEM"
> 
> Is this true? When I arbitrarily open up a QTR curve for K7 inks published by Piezography, I find exactly 256 gray values, for each there is an assignment of inks to be used. But 256 (8 bit) gray values, no more no less.
> 
> To be provocatine, I say even a single black only (BO) system can print 256 shades gray. To be fair, the multiple ink set-up of K7 (or K3 for that matter) will produce each of the 256 shades with greater smoothness and overall finess than a BO print. Using the 8 bit QTR set-up, both BO and multi K will each produce 256 shades of gray.
> 
> I think some people do not realize that if your image is 8 bit, there are 256 shades available, and no interpolation between them is allowed. Even if the ink/paper system is capable of producing more shades than 256, it is never achieved in reality. The same applies even if your image is 16 bits, because QTR curves are described in 8 bit architecture.
> 
> In summary, on one single paper, K7, K3, or BO all produce AT MOST 256 shades of gray. It can be argued that using ABW on that same paper, you can actually produce many, many more shades of "near-neutral gray", but only 256 at a time. Again, ABW gets maligned in a manner that has no basis in fact.
> 
> Did I get this all wrong? Is there something to this that eludes my mind? Or is the ".........tens of thousands more gray value ....." just poetic waxing?
> 
> I concede there are some reasons to chose multi K systems like Piezography K7, but greater number of gray shades?
> 
> Shilesh
>

Re: [Digital BW] Re: How Many Shades of Gray - K7 vs K3?

2011-03-21 by Ernst Dinkla

While there is consensus that 16-bit K7 improves on K3 in general it 
would surprise me if 16-bit K7 isn't over the top considering the actual 
resolution + tone reproduction of the best paper coatings we have. To 
what value either on 16-bit or on grey inks could it be reduced to match 
best print quality possible? Is an 8-bit K7 already beyond that quality 
(now), couldn't a 16-bit K4 printer be equal then? Not to mention 
droplet sizes and weaving structures. It isn't just Shilesh who asks 
those questions.

Prints in hand count but subjectivity then also creep in. If smoothness 
compromises acutance the observers may split in two groups and both are 
right. Pixel peeping has been criticised for good reasons but at the 
same time digital photography made enormous progress due to the 
technical improvements that gave us more and better pixels. I have not 
seen MTF charts of inkjet papers/inks/printers, maybe it is time for a 
practical solution to get that kind of information on the table.

-- 
Met vriendelijke groeten,   Ernst

Try: http://tech.groups.yahoo.com/group/Wide_Inkjet_Printers/

|      Dinkla Grafische Techniek      |
|         www.pigment-print.com        |
|                 ( unvollendet )                 |

Re: How Many Shades of Gray - K7 vs K3?

2011-03-21 by shileshjani

Thank you for clarifying that Roy.

So let us take a hypothetical situation:

We have a square with a value of 128 (mid value in 8 bit), and print that square. It will look up in the QTR curve for row 128 of each ink to lay down the inks.

If we have our image in 16 bits (total discrete levels is 2^16 = 65536), mid point is 23768. We cannot select this gray point in Photoshop color picker as far as I know. But I can imagine it exists is a 16 bit gray file. If we pick +1 from mid-point (or 23768 + 1 = 23769), how will QTR assign inks for this spot? Will it interpolate all inks values between 128 and 129 in the QTR curve description?

I know this does not have anything to do with K3 vs K7.

Shilesh

 

--- In DigitalBlackandWhiteThePrint@yahoogroups.com, "Roy" <roy@...> wrote:
Show quoted textHide quoted text
>
> Hi Shilesh,
> 
> Sorry but I have to disagree with this -- especially: QTR curves are 16-bit not 8-bit.   
> Yes there are 256 points but each one is a 16-bit value.
> > I think some people do not realize that if your image is 8 bit, there are 256 shades available,
> > and no interpolation between them is allowed. Even if the ink/paper system is capable of 
> > producing more shades than 256, it is never achieved in reality. The same applies even if 
> > your image is 16 bits, because QTR curves are described in 8 bit architecture.
> > 
> 
> I think the issue of 256 levels of gray is a misleading concept.  There are all these
> parts of the process that have specs of 8-bit or 256 values that it is very easy to fall 
> into the trap that the result print has to have 256 levels of gray.  But in real prints -- both
> digital and film -- the perception of gray is always an average of lots of pixels in the
> source and well as lots of dots of ink.   It's this averaging that fills in all the mid-grays
> between each of the 256 grays -- essentially making a continuous print.  
> 
> On a print I can pretty easily see the difference between steps that are 1 unit apart
> in 256 grays and 16-bit gradient across those same values.  (3800, K3 OEM inks & QTR)
> 
> So whether you are using K7, K3, or BO you will get more than 256 grays.  The difference
> is mainly seeing dots in the BO case -- the dark black dots on white paper have
> enough contrast that you see them with the naked eye.   I think the K3 LLK ink is
> light enough that you don't see them -- and I mean get up close and look critically.
> Most of my prints come from 4x5 film, tmax 100 and the grain from the film is more
> obvious than the grain from the dots.   The K7 light inks are lighter still and can
> stand more magnification before seeing the dots.   Tyler's article illustrates this,
> but the main thing I get from his scans is the dot resolution of the print is the most
> important factor -- 2880dpi is better than 1440dpi, and the silver dpi is still much
> better than that.
> 
> The things I think are important are using 16-bit for all editing from 16-bit scan
> or raw digital.  Use all the resolution you can.  QTR will use up to 720ppi, the
> Epson driver with use this on most printers if you select Finest Detail.
> To get great prints most things boil down to starting with the best image and
> knowing now to edit and get what you want it to look like.
> 
> ---------------
> 
> As far as what inks to use -- they are all good but there are tradeoffs and different
> amounts of work to get there.   Probably the biggest aesthetic decision is matte
> versus photo paper -- and within each category there are lots of choices.
> 
> K7 is great in that most is fixed and done for you.  K3 is great in that you have
> fine tuning control of color tone including split tones if you use QTR.  Glossy
> papers are often problematic and need GLOP but I find Harman Gloss Baryta
> does really well with Epson K3 inks straight as is.
> 
> Roy
> 
> --- In DigitalBlackandWhiteThePrint@yahoogroups.com, "shileshjani" <janishilesh@> wrote:
> >
> > I just read an interesting post by Jon Cone here:
> > 
> > http://www.piezography.com/PiezoPress/blog/piezography-technical/making-a-fine-piezography-print/
> > 
> > He says on page 2 of the pdf:
> > 
> > "Because Piezography with four or as many as seven distinct shades of ink can separate more tonal values than can the OEM three shade systems, it is important to start with very smooth image files that have a long tonal scale. Without going into mathematics and the virtues of using overlapping shades of Piezography inks rather than the interlinking shades of the OEM, the Piezography system produces tens of thousands more gray value combinations than can the OEM"
> > 
> > Is this true? When I arbitrarily open up a QTR curve for K7 inks published by Piezography, I find exactly 256 gray values, for each there is an assignment of inks to be used. But 256 (8 bit) gray values, no more no less.
> > 
> > To be provocatine, I say even a single black only (BO) system can print 256 shades gray. To be fair, the multiple ink set-up of K7 (or K3 for that matter) will produce each of the 256 shades with greater smoothness and overall finess than a BO print. Using the 8 bit QTR set-up, both BO and multi K will each produce 256 shades of gray.
> > 
> > I think some people do not realize that if your image is 8 bit, there are 256 shades available, and no interpolation between them is allowed. Even if the ink/paper system is capable of producing more shades than 256, it is never achieved in reality. The same applies even if your image is 16 bits, because QTR curves are described in 8 bit architecture.
> > 
> > In summary, on one single paper, K7, K3, or BO all produce AT MOST 256 shades of gray. It can be argued that using ABW on that same paper, you can actually produce many, many more shades of "near-neutral gray", but only 256 at a time. Again, ABW gets maligned in a manner that has no basis in fact.
> > 
> > Did I get this all wrong? Is there something to this that eludes my mind? Or is the ".........tens of thousands more gray value ....." just poetic waxing?
> > 
> > I concede there are some reasons to chose multi K systems like Piezography K7, but greater number of gray shades?
> > 
> > Shilesh
> >
>

Re: How Many Shades of Gray - K7 vs K3?

2011-03-21 by Paul

Ernst Dinkla <edinkla@...> wrote:
>
> ... it would surprise me if 16-bit K7 isn't over the top 
> considering the actual resolution + tone reproduction of 
> the best paper coatings we have.

I was looking just at the resolution issue with different papers, using a traditional line pair/mm type of test file.  The lines were pure black and pure white, producing no information about what happens with gray values.  At any rate, a few tentative conclusions I reached were that bleed (from the black boost and otherwise) and printer limitations may be significant factors.  For what it's worth, I've posted a Jpeg of the 4800 dpi scan at 
Arches-PaSmFa205-IlfSmGloss-4800scans-720-res.jpg

The papers are Arches un-coated watercolor paper, Premier Art Smooth Fine Art 205 (Epson Scrapbook paper), and Ilford Gallery Smooth glossy.

With Arches uncoated watercolor paper I had previously found that holding down the midtone ink limits was critical.  So, for the best Arches print, I suspect I'll need the full Eboni-6 as opposed to the Eboni-4 that, on coated paper, I find visually equal to Eboni-6.  When the ink limits are held way down to avoid bleed, paper overload, and visible dots the need for the lighter inks and the full 6 dilutions is much greater, and the "serial" (?) partitioning of QTR's standard profiling makes a better print than when I use various options to have more inks firing at the same time.

Aside from bleed, I think we may be at the printers' limitations to lay down accurate dots.  The Epson 1400 I'm using is getting old, and that could also be a factor.  (Having made a few trips into the High Sierras on a mule probably hasn't helped this old workhorse of a printer either.)

I also made test prints with Epson Claria K on glossy paper.  While prints from the Noritsu-based similar dyes look sharper than the glossy pigment prints, on the test charts the pigments look sharper -- not sure if this is bleed or some other factor. 


> ... I have not seen MTF charts of inkjet papers/inks/printers ... 

That would be interesting.  I don't think measuring MTF would be within what most of us could do.  As a substitute, and similar to what the pre-MTF lens testers did, I once printed a resolution chart that used a midtone value (like 50%) as opposed to the pure black (100%) lines.  It could provide at least one more data point.  I can't find that now, but my vague memory is that is was similar to the results with the black line chart.  

(I'm now looking at a different issue.  The Eb-4 tests look totally different now than a week ago.  We're in a rain storm.  Does humidity make a huge difference in dmax and tone due to the coatings' inability to hold as much ink?  Sometimes I want to dust of the enlarger...)

Paul
www.PaulRoark.com

Re: How Many Shades of Gray - K7 vs K3?

2011-03-21 by dlruckus

I sometimes wonder if the ink base constituents don't remain active within the coatings and paper much longer than we realize.Perhaps, like gelatin, sensitivity to humidity can alter the visual and physical attributes over a very long period of time.
Regards,
Duane


--- In DigitalBlackandWhiteThePrint@yahoogroups.com, "Paul" <roark.paul@...> wrote:
Show quoted textHide quoted text
> (I'm now looking at a different issue.  The Eb-4 tests look totally different now than a week ago.  We're in a rain storm.  Does humidity make a huge difference in dmax and tone due to the coatings' inability to hold as much ink?  Sometimes I want to dust of the enlarger...)
> 
> Paul
> www.PaulRoark.com
>

Re: How Many Shades of Gray - K7 vs K3?

2011-03-21 by Keith

Paul wrote;
> 
> (I'm now looking at a different issue.  The Eb-4 tests look totally different now than a week ago.  We're in a rain storm.  Does humidity make a huge difference in dmax and tone due to the coatings' inability to hold as much ink?  Sometimes I want to dust of the enlarger...)
> 
> Paul
> www.PaulRoark.com
>


I do Cyanotypes on Arche HP and find that the drier the paper the higher the Dmax. Presumably drier paper sucks in more sensitiser, also the contrast to the eye seems higher.

However with an inket only firing a set amount of ink, you would need to up the amount of ink. This would present the problem of knowing the humidity of the paper at print time.

Just my two penny-worth.

Keith

Re: How Many Shades of Gray - K7 vs K3?

2011-03-21 by piezobw

Paul,

I think I read that you are making homemade ink bases for these tests or using some combination of materials.

That might be the instability of tone and dMax.

regards,

Jon

--- In DigitalBlackandWhiteThePrint@yahoogroups.com, "Paul" <roark.paul@...> wrote:
Show quoted textHide quoted text
> (I'm now looking at a different issue.  The Eb-4 tests look totally different now than a week ago.  We're in a rain storm.  Does humidity make a huge difference in dmax and tone due to the coatings' inability to hold as much ink?  Sometimes I want to dust of the enlarger...)
> 
> Paul
> www.PaulRoark.com
>

RE: [Digital BW] Re: How Many Shades of Gray - K7 vs K3?

2011-03-21 by E.Neilsen

Keith, You may be able to get a higher Dmax with a drier paper, because you
have less fog caused by the moisture in the paper stating the reaction to
form the image. No fog, longer exposure, better local contrast, better Dmax.


 

and to the K3, K7  range question. Jon really said a great couple of line in
his response here with, " Sometimes, in all of this interesting technology
with all the bits (no pun intended), seeing is believing, rather than trying
to sort it out in an intellectual manner. I don't think that you can ever
resolve something aesthetic through reasoning.

However, the most important thing is that you're happy with the results you
are producing. So, if you have doubts, if you think that they could be
better, or if you think they are not as good as your analogue work was -
then probably it isn't - and you should really look at the physical evidence
of prints by comparison. I think looking at comparative prints is where
eventually you will find the answers to whether your printing process is as
strong as you want or as strong as you need."

 

I too was at that print sharing in NYC after PPE. I still have the shots
from inside Amadou Diallo studio. Yes, there was amazing similarity in the
prints. And a perfect example of casual viewing under less than perfect
lighting all with pixel peeping. 

 

To me the bottom line rest with the human eyes and mind that control the
printer, ink paper combination at hand. Within each set up lies better, best
and optimal. It is up to you to know when, how, why to make the edit match
the paper, match the ______ if you are trying to hit a specific. It is also
up to you, to know when to just feel the process and know how to push back. 

 

  

 

 

Eric Neilsen

Eric Neilsen Photography

4101 Commerce Street, Suite 9

Dallas, TX 75226

 

www.ericneilsenphotography.com

skype me with ejprinter

www.ericneilsenphotography.com/forum1

Let's Talk Photography

 



[Non-text portions of this message have been removed]

Re: How Many Shades of Gray - K7 vs K3?

2011-03-21 by Paul

"piezobw" <jon@...> wrote:
>
> Paul,
> 
> I think I read that you are making homemade ink bases for these tests or using some combination of materials.
> 
> That might be the instability of tone and dMax.
> 
> regards,
> 

These were commercial inks.

Paul
www.PaulRoark.com

Re: How Many Shades of Gray - K7 vs K3?

2011-03-21 by Paul

"Keith" <keithdale@...> wrote:
>
>...
> I do Cyanotypes on Arche HP and find that the drier the paper the higher the Dmax. Presumably drier paper sucks in more sensitiser, also the contrast to the eye seems higher.


I tried using a drier on one test strip before printing it with no significant effect.  

I worry more about the repeatability and reliability of profiles than the dmax.  I'm in the process of making less sensitive curves now.

Paul
www.PaulRoark.com

Re: How Many Shades of Gray - K7 vs K3?

2011-03-22 by Roy

--- In DigitalBlackandWhiteThePrint@yahoogroups.com, "shileshjani" <janishilesh@...> wrote:
>
> Thank you for clarifying that Roy.
> 
> So let us take a hypothetical situation:
> 
> We have a square with a value of 128 (mid value in 8 bit), and print that square. It will look up in the QTR curve for row 128 of each ink to lay down the inks.
> 
> If we have our image in 16 bits (total discrete levels is 2^16 = 65536), mid point is 23768. We cannot select this gray point in Photoshop color picker as far as I know. But I can imagine it exists is a 16 bit gray file. If we pick +1 from mid-point (or 23768 + 1 = 23769), how will QTR assign inks for this spot? Will it interpolate all inks values between 128 and 129 in the QTR curve description?

Shilesh,

Photoshop lacks easy ways to set specific 16-bit values but you can see them with
the Info palette -- select 16-bit.   Note that 16-bit is really 0-32768 which is more
like 15 bit but that's another story.  But internally with 16-bit files all the arithmetic
is done in 16-bit so you don't lose any data.

Here's a way to do an experiment to show what goes on.

Create a 16-bit grayscale file - say 8in wide by 2in tall.   Make top left black and
top right white, on the bottom half make a long gradient from black to white.
Set up your Info palette for gray 16-bit and see the values.
Now shrink all the values in the file to the range 128 to 129.  Do this with the
Levels command, setting the Output values to 128 and 129.   The whole file should
be essentially all middle gray.   But use the Info palette and see top left = 16450 and
top right = 16577,  on the bottom you can see the gradient for the same range.
On a good screen you might see the border between sides.  (even the bottom may
show it because only 8-bits is passed to the display).

Print this on your favorite paper and set of curves.  If you look close you should see
a dividing line in the middle on the top but not at the bottom.  If you have an accurate
spectro all the better.   The two top patches will give consist measurements in
various places.  On the bottom you should be able to see lots of intermediate values
between the two top measurements -- with a very accurate gradient.

To make it even more interesting convert that 16-bit file to 8-bit and print it
again.   You'll find the prints to be virtually identical -- gradient and all.   Yes
the 8-bit file will show all the intermediate grays in the print that the 16-bit
file showed.  In the gradient some of the pixels are 128 and some 129 - with
the mix ratio providing the extra information that you probably think was lost.

To answer your question about how QTR works.  On the Mac if you send QTR the
16-bit data (check 16-bit in PS and in QTR), QTR will linearly interpolate the
values from the .quad file between 128 and 129.  On PCs or Mac where you don't
set 16-bit, it'll work like the second case above.  Note that the 16 to 8 bit
conversion has to be done intelligently -- PS and QTR both do this.

Try this out.  It's really worth seeing for yourself.
 
Roy
Show quoted textHide quoted text
> 
> I know this does not have anything to do with K3 vs K7.
> 
> Shilesh
> 
>  
> 
> --- In DigitalBlackandWhiteThePrint@yahoogroups.com, "Roy" <roy@> wrote:
> >
> > Hi Shilesh,
> > 
> > Sorry but I have to disagree with this -- especially: QTR curves are 16-bit not 8-bit.   
> > Yes there are 256 points but each one is a 16-bit value.
> > > I think some people do not realize that if your image is 8 bit, there are 256 shades available,
> > > and no interpolation between them is allowed. Even if the ink/paper system is capable of 
> > > producing more shades than 256, it is never achieved in reality. The same applies even if 
> > > your image is 16 bits, because QTR curves are described in 8 bit architecture.
> > > 
> > 
> > I think the issue of 256 levels of gray is a misleading concept.  There are all these
> > parts of the process that have specs of 8-bit or 256 values that it is very easy to fall 
> > into the trap that the result print has to have 256 levels of gray.  But in real prints -- both
> > digital and film -- the perception of gray is always an average of lots of pixels in the
> > source and well as lots of dots of ink.   It's this averaging that fills in all the mid-grays
> > between each of the 256 grays -- essentially making a continuous print.  
> > 
> > On a print I can pretty easily see the difference between steps that are 1 unit apart
> > in 256 grays and 16-bit gradient across those same values.  (3800, K3 OEM inks & QTR)
> > 
> > So whether you are using K7, K3, or BO you will get more than 256 grays.  The difference
> > is mainly seeing dots in the BO case -- the dark black dots on white paper have
> > enough contrast that you see them with the naked eye.   I think the K3 LLK ink is
> > light enough that you don't see them -- and I mean get up close and look critically.
> > Most of my prints come from 4x5 film, tmax 100 and the grain from the film is more
> > obvious than the grain from the dots.   The K7 light inks are lighter still and can
> > stand more magnification before seeing the dots.   Tyler's article illustrates this,
> > but the main thing I get from his scans is the dot resolution of the print is the most
> > important factor -- 2880dpi is better than 1440dpi, and the silver dpi is still much
> > better than that.
> > 
> > The things I think are important are using 16-bit for all editing from 16-bit scan
> > or raw digital.  Use all the resolution you can.  QTR will use up to 720ppi, the
> > Epson driver with use this on most printers if you select Finest Detail.
> > To get great prints most things boil down to starting with the best image and
> > knowing now to edit and get what you want it to look like.
> > 
> > ---------------
> > 
> > As far as what inks to use -- they are all good but there are tradeoffs and different
> > amounts of work to get there.   Probably the biggest aesthetic decision is matte
> > versus photo paper -- and within each category there are lots of choices.
> > 
> > K7 is great in that most is fixed and done for you.  K3 is great in that you have
> > fine tuning control of color tone including split tones if you use QTR.  Glossy
> > papers are often problematic and need GLOP but I find Harman Gloss Baryta
> > does really well with Epson K3 inks straight as is.
> > 
> > Roy
> > 
> > --- In DigitalBlackandWhiteThePrint@yahoogroups.com, "shileshjani" <janishilesh@> wrote:
> > >
> > > I just read an interesting post by Jon Cone here:
> > > 
> > > http://www.piezography.com/PiezoPress/blog/piezography-technical/making-a-fine-piezography-print/
> > > 
> > > He says on page 2 of the pdf:
> > > 
> > > "Because Piezography with four or as many as seven distinct shades of ink can separate more tonal values than can the OEM three shade systems, it is important to start with very smooth image files that have a long tonal scale. Without going into mathematics and the virtues of using overlapping shades of Piezography inks rather than the interlinking shades of the OEM, the Piezography system produces tens of thousands more gray value combinations than can the OEM"
> > > 
> > > Is this true? When I arbitrarily open up a QTR curve for K7 inks published by Piezography, I find exactly 256 gray values, for each there is an assignment of inks to be used. But 256 (8 bit) gray values, no more no less.
> > > 
> > > To be provocatine, I say even a single black only (BO) system can print 256 shades gray. To be fair, the multiple ink set-up of K7 (or K3 for that matter) will produce each of the 256 shades with greater smoothness and overall finess than a BO print. Using the 8 bit QTR set-up, both BO and multi K will each produce 256 shades of gray.
> > > 
> > > I think some people do not realize that if your image is 8 bit, there are 256 shades available, and no interpolation between them is allowed. Even if the ink/paper system is capable of producing more shades than 256, it is never achieved in reality. The same applies even if your image is 16 bits, because QTR curves are described in 8 bit architecture.
> > > 
> > > In summary, on one single paper, K7, K3, or BO all produce AT MOST 256 shades of gray. It can be argued that using ABW on that same paper, you can actually produce many, many more shades of "near-neutral gray", but only 256 at a time. Again, ABW gets maligned in a manner that has no basis in fact.
> > > 
> > > Did I get this all wrong? Is there something to this that eludes my mind? Or is the ".........tens of thousands more gray value ....." just poetic waxing?
> > > 
> > > I concede there are some reasons to chose multi K systems like Piezography K7, but greater number of gray shades?
> > > 
> > > Shilesh
> > >
> >
>

Re: How Many Shades of Gray - K7 vs K3?

2011-03-22 by shileshjani

Roy,

I am doing a simple experiment similar to what you suggest. I started it before I read your message, so I will keep on for now. I am trying to see if I can create a gradient between 45 and 50% steps, and print it measurably at between these two ends.

My file is in 16 bits, but my PC based Photoshop only allows info pallet in 8 bits. Is it because I am on XP 32 bit? It is printing as I write this.

Any event, the print just came out. Let me measure.................


..........Sure enough, there is measurably increasing density going from 45% to 50%, even at measuring steps smaller than the size of the spectro aperature.

Wow - just wow. Thank you for pointing these subtleties, and more importantly explaining these to me. I have always known that the display does not show all that is in the file, but to realize that the printer is actually printing all this hidden-from-view information is a revelation for me.

I am particularly thrilled that I have yet to measure a tone reversal even when measuring L values spaced approximately 0.05 units. That is really impressive. I am happy with those QTR curves I created.

Thank you!!!

Shilesh

PS: This may be old news to many of you who have dealt in this level of detail, but cannot say how much a revelation this is. 



--- In DigitalBlackandWhiteThePrint@yahoogroups.com, "Roy" <roy@...> wrote:
Show quoted textHide quoted text
>
> 
> 
> --- In DigitalBlackandWhiteThePrint@yahoogroups.com, "shileshjani" <janishilesh@> wrote:
> >
> > Thank you for clarifying that Roy.
> > 
> > So let us take a hypothetical situation:
> > 
> > We have a square with a value of 128 (mid value in 8 bit), and print that square. It will look up in the QTR curve for row 128 of each ink to lay down the inks.
> > 
> > If we have our image in 16 bits (total discrete levels is 2^16 = 65536), mid point is 23768. We cannot select this gray point in Photoshop color picker as far as I know. But I can imagine it exists is a 16 bit gray file. If we pick +1 from mid-point (or 23768 + 1 = 23769), how will QTR assign inks for this spot? Will it interpolate all inks values between 128 and 129 in the QTR curve description?
> 
> Shilesh,
> 
> Photoshop lacks easy ways to set specific 16-bit values but you can see them with
> the Info palette -- select 16-bit.   Note that 16-bit is really 0-32768 which is more
> like 15 bit but that's another story.  But internally with 16-bit files all the arithmetic
> is done in 16-bit so you don't lose any data.
> 
> Here's a way to do an experiment to show what goes on.
> 
> Create a 16-bit grayscale file - say 8in wide by 2in tall.   Make top left black and
> top right white, on the bottom half make a long gradient from black to white.
> Set up your Info palette for gray 16-bit and see the values.
> Now shrink all the values in the file to the range 128 to 129.  Do this with the
> Levels command, setting the Output values to 128 and 129.   The whole file should
> be essentially all middle gray.   But use the Info palette and see top left = 16450 and
> top right = 16577,  on the bottom you can see the gradient for the same range.
> On a good screen you might see the border between sides.  (even the bottom may
> show it because only 8-bits is passed to the display).
> 
> Print this on your favorite paper and set of curves.  If you look close you should see
> a dividing line in the middle on the top but not at the bottom.  If you have an accurate
> spectro all the better.   The two top patches will give consist measurements in
> various places.  On the bottom you should be able to see lots of intermediate values
> between the two top measurements -- with a very accurate gradient.
> 
> To make it even more interesting convert that 16-bit file to 8-bit and print it
> again.   You'll find the prints to be virtually identical -- gradient and all.   Yes
> the 8-bit file will show all the intermediate grays in the print that the 16-bit
> file showed.  In the gradient some of the pixels are 128 and some 129 - with
> the mix ratio providing the extra information that you probably think was lost.
> 
> To answer your question about how QTR works.  On the Mac if you send QTR the
> 16-bit data (check 16-bit in PS and in QTR), QTR will linearly interpolate the
> values from the .quad file between 128 and 129.  On PCs or Mac where you don't
> set 16-bit, it'll work like the second case above.  Note that the 16 to 8 bit
> conversion has to be done intelligently -- PS and QTR both do this.
> 
> Try this out.  It's really worth seeing for yourself.
>  
> Roy
> 
> > 
> > I know this does not have anything to do with K3 vs K7.
> > 
> > Shilesh
> > 
> >  
> > 
> > --- In DigitalBlackandWhiteThePrint@yahoogroups.com, "Roy" <roy@> wrote:
> > >
> > > Hi Shilesh,
> > > 
> > > Sorry but I have to disagree with this -- especially: QTR curves are 16-bit not 8-bit.   
> > > Yes there are 256 points but each one is a 16-bit value.
> > > > I think some people do not realize that if your image is 8 bit, there are 256 shades available,
> > > > and no interpolation between them is allowed. Even if the ink/paper system is capable of 
> > > > producing more shades than 256, it is never achieved in reality. The same applies even if 
> > > > your image is 16 bits, because QTR curves are described in 8 bit architecture.
> > > > 
> > > 
> > > I think the issue of 256 levels of gray is a misleading concept.  There are all these
> > > parts of the process that have specs of 8-bit or 256 values that it is very easy to fall 
> > > into the trap that the result print has to have 256 levels of gray.  But in real prints -- both
> > > digital and film -- the perception of gray is always an average of lots of pixels in the
> > > source and well as lots of dots of ink.   It's this averaging that fills in all the mid-grays
> > > between each of the 256 grays -- essentially making a continuous print.  
> > > 
> > > On a print I can pretty easily see the difference between steps that are 1 unit apart
> > > in 256 grays and 16-bit gradient across those same values.  (3800, K3 OEM inks & QTR)
> > > 
> > > So whether you are using K7, K3, or BO you will get more than 256 grays.  The difference
> > > is mainly seeing dots in the BO case -- the dark black dots on white paper have
> > > enough contrast that you see them with the naked eye.   I think the K3 LLK ink is
> > > light enough that you don't see them -- and I mean get up close and look critically.
> > > Most of my prints come from 4x5 film, tmax 100 and the grain from the film is more
> > > obvious than the grain from the dots.   The K7 light inks are lighter still and can
> > > stand more magnification before seeing the dots.   Tyler's article illustrates this,
> > > but the main thing I get from his scans is the dot resolution of the print is the most
> > > important factor -- 2880dpi is better than 1440dpi, and the silver dpi is still much
> > > better than that.
> > > 
> > > The things I think are important are using 16-bit for all editing from 16-bit scan
> > > or raw digital.  Use all the resolution you can.  QTR will use up to 720ppi, the
> > > Epson driver with use this on most printers if you select Finest Detail.
> > > To get great prints most things boil down to starting with the best image and
> > > knowing now to edit and get what you want it to look like.
> > > 
> > > ---------------
> > > 
> > > As far as what inks to use -- they are all good but there are tradeoffs and different
> > > amounts of work to get there.   Probably the biggest aesthetic decision is matte
> > > versus photo paper -- and within each category there are lots of choices.
> > > 
> > > K7 is great in that most is fixed and done for you.  K3 is great in that you have
> > > fine tuning control of color tone including split tones if you use QTR.  Glossy
> > > papers are often problematic and need GLOP but I find Harman Gloss Baryta
> > > does really well with Epson K3 inks straight as is.
> > > 
> > > Roy
> > > 
> > > --- In DigitalBlackandWhiteThePrint@yahoogroups.com, "shileshjani" <janishilesh@> wrote:
> > > >
> > > > I just read an interesting post by Jon Cone here:
> > > > 
> > > > http://www.piezography.com/PiezoPress/blog/piezography-technical/making-a-fine-piezography-print/
> > > > 
> > > > He says on page 2 of the pdf:
> > > > 
> > > > "Because Piezography with four or as many as seven distinct shades of ink can separate more tonal values than can the OEM three shade systems, it is important to start with very smooth image files that have a long tonal scale. Without going into mathematics and the virtues of using overlapping shades of Piezography inks rather than the interlinking shades of the OEM, the Piezography system produces tens of thousands more gray value combinations than can the OEM"
> > > > 
> > > > Is this true? When I arbitrarily open up a QTR curve for K7 inks published by Piezography, I find exactly 256 gray values, for each there is an assignment of inks to be used. But 256 (8 bit) gray values, no more no less.
> > > > 
> > > > To be provocatine, I say even a single black only (BO) system can print 256 shades gray. To be fair, the multiple ink set-up of K7 (or K3 for that matter) will produce each of the 256 shades with greater smoothness and overall finess than a BO print. Using the 8 bit QTR set-up, both BO and multi K will each produce 256 shades of gray.
> > > > 
> > > > I think some people do not realize that if your image is 8 bit, there are 256 shades available, and no interpolation between them is allowed. Even if the ink/paper system is capable of producing more shades than 256, it is never achieved in reality. The same applies even if your image is 16 bits, because QTR curves are described in 8 bit architecture.
> > > > 
> > > > In summary, on one single paper, K7, K3, or BO all produce AT MOST 256 shades of gray. It can be argued that using ABW on that same paper, you can actually produce many, many more shades of "near-neutral gray", but only 256 at a time. Again, ABW gets maligned in a manner that has no basis in fact.
> > > > 
> > > > Did I get this all wrong? Is there something to this that eludes my mind? Or is the ".........tens of thousands more gray value ....." just poetic waxing?
> > > > 
> > > > I concede there are some reasons to chose multi K systems like Piezography K7, but greater number of gray shades?
> > > > 
> > > > Shilesh
> > > >
> > >
> >
>

Re: How Many Shades of Gray - K7 vs K3?

2011-03-22 by tboleyyh

as Mike King pointed out to me some years back, Bill Atkinson has a 16 bit 1024 levels of gray file also useful for similar testing. His new share site is here-
https://public.me.com/billatkinson
It's RGB, but rather than convert as is to gray, you're safer deleting 2 channels then mode changing to gray, which simply assigns gray and no conversions are made.
Tyler

--- In DigitalBlackandWhiteThePrint@yahoogroups.com, "shileshjani" <janishilesh@...> wrote:
Show quoted textHide quoted text
>
> ...that the printer is actually printing all this hidden-from-view
> information is a revelation for me.

Re: How Many Shades of Gray - K7 vs K3?

2011-03-22 by shileshjani

Thank you, Tyler. I will look at that.

Shilesh

--- In DigitalBlackandWhiteThePrint@yahoogroups.com, "tboleyyh" <tyler@...> wrote:
Show quoted textHide quoted text
>
> as Mike King pointed out to me some years back, Bill Atkinson has a 16 bit 1024 levels of gray file also useful for similar testing. His new share site is here-
> https://public.me.com/billatkinson
> It's RGB, but rather than convert as is to gray, you're safer deleting 2 channels then mode changing to gray, which simply assigns gray and no conversions are made.
> Tyler
> 
> --- In DigitalBlackandWhiteThePrint@yahoogroups.com, "shileshjani" <janishilesh@> wrote:
> >
> > ...that the printer is actually printing all this hidden-from-view
> > information is a revelation for me.
>

Re: How Many Shades of Gray - K7 vs K3?

2011-03-22 by Roy

--- In DigitalBlackandWhiteThePrint@yahoogroups.com, "shileshjani" <janishilesh@...> wrote:
...
> 
> My file is in 16 bits, but my PC based Photoshop only allows info pallet in 8 bits. Is it because I am on XP 32 bit? It is printing as I write this.
> 
> Shilesh
> 

It's a little hidden.  The pulldown on the upper right called Panel Options...
does not have the bit selection for some reason.  You need to use the little triangle
next to the eyedropper on the info palette to find the #bits selection.

Roy

Re: How Many Shades of Gray - K7 vs K3?

2011-03-23 by shileshjani

I found that 16 bit selection. Thank you for that tip, Roy.

I am still in awe of all these levels available to be printed, and to measure them on an actual print is quite unexpected for me.

Shilesh

--- In DigitalBlackandWhiteThePrint@yahoogroups.com, "Roy" <roy@...> wrote:
Show quoted textHide quoted text
>
> 
> --- In DigitalBlackandWhiteThePrint@yahoogroups.com, "shileshjani" <janishilesh@> wrote:
> ...
> > 
> > My file is in 16 bits, but my PC based Photoshop only allows info pallet in 8 bits. Is it because I am on XP 32 bit? It is printing as I write this.
> > 
> > Shilesh
> > 
> 
> It's a little hidden.  The pulldown on the upper right called Panel Options...
> does not have the bit selection for some reason.  You need to use the little triangle
> next to the eyedropper on the info palette to find the #bits selection.
> 
> Roy
>

Re: How Many Shades of Gray - K7 vs K3?

2011-03-23 by shileshjani

Roy,

I have now repeated that experiment using QTR and ABW on my 4880. I have been measuring in steps of L=0.05 very easily, +/- 0.01 depending on how much I manually move the spectro on the paper. So this tells me that K3+Color (I am using LM and LC in my QTR setup), and ABW (presumably K3+5 colors) each is perfectly capable of producing gray shades in the range of 5,000 values (L going from 0 to 100 in steps of 0.05 = 5,000 steps). I know that paper white is never L=100 and Dmax is never L=0. But still, we are looking at a LOT of gray levels that can be printed, and measured very readily.

So why is there so much (mis)information online that we are limited to 256 shades of gray at best? Is that you walked me through not widely known or appreciated?

Shilesh



--- In DigitalBlackandWhiteThePrint@yahoogroups.com, "Roy" <roy@...> wrote:
Show quoted textHide quoted text
>
> 
> 
> --- In DigitalBlackandWhiteThePrint@yahoogroups.com, "shileshjani" <janishilesh@> wrote:
> >
> > Thank you for clarifying that Roy.
> > 
> > So let us take a hypothetical situation:
> > 
> > We have a square with a value of 128 (mid value in 8 bit), and print that square. It will look up in the QTR curve for row 128 of each ink to lay down the inks.
> > 
> > If we have our image in 16 bits (total discrete levels is 2^16 = 65536), mid point is 23768. We cannot select this gray point in Photoshop color picker as far as I know. But I can imagine it exists is a 16 bit gray file. If we pick +1 from mid-point (or 23768 + 1 = 23769), how will QTR assign inks for this spot? Will it interpolate all inks values between 128 and 129 in the QTR curve description?
> 
> Shilesh,
> 
> Photoshop lacks easy ways to set specific 16-bit values but you can see them with
> the Info palette -- select 16-bit.   Note that 16-bit is really 0-32768 which is more
> like 15 bit but that's another story.  But internally with 16-bit files all the arithmetic
> is done in 16-bit so you don't lose any data.
> 
> Here's a way to do an experiment to show what goes on.
> 
> Create a 16-bit grayscale file - say 8in wide by 2in tall.   Make top left black and
> top right white, on the bottom half make a long gradient from black to white.
> Set up your Info palette for gray 16-bit and see the values.
> Now shrink all the values in the file to the range 128 to 129.  Do this with the
> Levels command, setting the Output values to 128 and 129.   The whole file should
> be essentially all middle gray.   But use the Info palette and see top left = 16450 and
> top right = 16577,  on the bottom you can see the gradient for the same range.
> On a good screen you might see the border between sides.  (even the bottom may
> show it because only 8-bits is passed to the display).
> 
> Print this on your favorite paper and set of curves.  If you look close you should see
> a dividing line in the middle on the top but not at the bottom.  If you have an accurate
> spectro all the better.   The two top patches will give consist measurements in
> various places.  On the bottom you should be able to see lots of intermediate values
> between the two top measurements -- with a very accurate gradient.
> 
> To make it even more interesting convert that 16-bit file to 8-bit and print it
> again.   You'll find the prints to be virtually identical -- gradient and all.   Yes
> the 8-bit file will show all the intermediate grays in the print that the 16-bit
> file showed.  In the gradient some of the pixels are 128 and some 129 - with
> the mix ratio providing the extra information that you probably think was lost.
> 
> To answer your question about how QTR works.  On the Mac if you send QTR the
> 16-bit data (check 16-bit in PS and in QTR), QTR will linearly interpolate the
> values from the .quad file between 128 and 129.  On PCs or Mac where you don't
> set 16-bit, it'll work like the second case above.  Note that the 16 to 8 bit
> conversion has to be done intelligently -- PS and QTR both do this.
> 
> Try this out.  It's really worth seeing for yourself.
>  
> Roy
> 
> > 
> > I know this does not have anything to do with K3 vs K7.
> > 
> > Shilesh
> > 
> >  
> > 
> > --- In DigitalBlackandWhiteThePrint@yahoogroups.com, "Roy" <roy@> wrote:
> > >
> > > Hi Shilesh,
> > > 
> > > Sorry but I have to disagree with this -- especially: QTR curves are 16-bit not 8-bit.   
> > > Yes there are 256 points but each one is a 16-bit value.
> > > > I think some people do not realize that if your image is 8 bit, there are 256 shades available,
> > > > and no interpolation between them is allowed. Even if the ink/paper system is capable of 
> > > > producing more shades than 256, it is never achieved in reality. The same applies even if 
> > > > your image is 16 bits, because QTR curves are described in 8 bit architecture.
> > > > 
> > > 
> > > I think the issue of 256 levels of gray is a misleading concept.  There are all these
> > > parts of the process that have specs of 8-bit or 256 values that it is very easy to fall 
> > > into the trap that the result print has to have 256 levels of gray.  But in real prints -- both
> > > digital and film -- the perception of gray is always an average of lots of pixels in the
> > > source and well as lots of dots of ink.   It's this averaging that fills in all the mid-grays
> > > between each of the 256 grays -- essentially making a continuous print.  
> > > 
> > > On a print I can pretty easily see the difference between steps that are 1 unit apart
> > > in 256 grays and 16-bit gradient across those same values.  (3800, K3 OEM inks & QTR)
> > > 
> > > So whether you are using K7, K3, or BO you will get more than 256 grays.  The difference
> > > is mainly seeing dots in the BO case -- the dark black dots on white paper have
> > > enough contrast that you see them with the naked eye.   I think the K3 LLK ink is
> > > light enough that you don't see them -- and I mean get up close and look critically.
> > > Most of my prints come from 4x5 film, tmax 100 and the grain from the film is more
> > > obvious than the grain from the dots.   The K7 light inks are lighter still and can
> > > stand more magnification before seeing the dots.   Tyler's article illustrates this,
> > > but the main thing I get from his scans is the dot resolution of the print is the most
> > > important factor -- 2880dpi is better than 1440dpi, and the silver dpi is still much
> > > better than that.
> > > 
> > > The things I think are important are using 16-bit for all editing from 16-bit scan
> > > or raw digital.  Use all the resolution you can.  QTR will use up to 720ppi, the
> > > Epson driver with use this on most printers if you select Finest Detail.
> > > To get great prints most things boil down to starting with the best image and
> > > knowing now to edit and get what you want it to look like.
> > > 
> > > ---------------
> > > 
> > > As far as what inks to use -- they are all good but there are tradeoffs and different
> > > amounts of work to get there.   Probably the biggest aesthetic decision is matte
> > > versus photo paper -- and within each category there are lots of choices.
> > > 
> > > K7 is great in that most is fixed and done for you.  K3 is great in that you have
> > > fine tuning control of color tone including split tones if you use QTR.  Glossy
> > > papers are often problematic and need GLOP but I find Harman Gloss Baryta
> > > does really well with Epson K3 inks straight as is.
> > > 
> > > Roy
> > > 
> > > --- In DigitalBlackandWhiteThePrint@yahoogroups.com, "shileshjani" <janishilesh@> wrote:
> > > >
> > > > I just read an interesting post by Jon Cone here:
> > > > 
> > > > http://www.piezography.com/PiezoPress/blog/piezography-technical/making-a-fine-piezography-print/
> > > > 
> > > > He says on page 2 of the pdf:
> > > > 
> > > > "Because Piezography with four or as many as seven distinct shades of ink can separate more tonal values than can the OEM three shade systems, it is important to start with very smooth image files that have a long tonal scale. Without going into mathematics and the virtues of using overlapping shades of Piezography inks rather than the interlinking shades of the OEM, the Piezography system produces tens of thousands more gray value combinations than can the OEM"
> > > > 
> > > > Is this true? When I arbitrarily open up a QTR curve for K7 inks published by Piezography, I find exactly 256 gray values, for each there is an assignment of inks to be used. But 256 (8 bit) gray values, no more no less.
> > > > 
> > > > To be provocatine, I say even a single black only (BO) system can print 256 shades gray. To be fair, the multiple ink set-up of K7 (or K3 for that matter) will produce each of the 256 shades with greater smoothness and overall finess than a BO print. Using the 8 bit QTR set-up, both BO and multi K will each produce 256 shades of gray.
> > > > 
> > > > I think some people do not realize that if your image is 8 bit, there are 256 shades available, and no interpolation between them is allowed. Even if the ink/paper system is capable of producing more shades than 256, it is never achieved in reality. The same applies even if your image is 16 bits, because QTR curves are described in 8 bit architecture.
> > > > 
> > > > In summary, on one single paper, K7, K3, or BO all produce AT MOST 256 shades of gray. It can be argued that using ABW on that same paper, you can actually produce many, many more shades of "near-neutral gray", but only 256 at a time. Again, ABW gets maligned in a manner that has no basis in fact.
> > > > 
> > > > Did I get this all wrong? Is there something to this that eludes my mind? Or is the ".........tens of thousands more gray value ....." just poetic waxing?
> > > > 
> > > > I concede there are some reasons to chose multi K systems like Piezography K7, but greater number of gray shades?
> > > > 
> > > > Shilesh
> > > >
> > >
> >
>

Re: [Digital BW] Re: How Many Shades of Gray - K7 vs K3?

2011-03-23 by Ernst Dinkla

On 03/23/2011 04:35 AM, shileshjani wrote:

> But when I look up (mis)information online, the posts are replete with the idea that inkjet prints (especially OEM solutions) cannot print even the 256 shades of 8 bit files. Really curious. Is what you just walked me through not widely known, or appreciated?
>
> Shilesh


Shadow detail is often not so nicely divided in separate strokes that 
can be measured with the aperture of a spectrometer. It is the spot 
where high loads of inks next to one another still should be contained 
within their pixel/cell boundaries to create that detail. And bleeding 
of high density inks shifts tone in an area more than bleeding of low 
density inks, there is more density buffered in a black dot than in an 
LLK dot. If shades get lost it is there. On my greyscale steps I added 
high contrast lines but also a boundary with a low tone difference.

An unbalanced quad inkset or an unevenly spread inkload in partioning 
can create an unstable image quality. It may still print all the shades 
but they may not represent the same greyscale value today or tomorrow on 
different sheets of the same paper.


-- 
Met vriendelijke groeten,   Ernst

Try: http://tech.groups.yahoo.com/group/Wide_Inkjet_Printers/

|      Dinkla Grafische Techniek      |
|         www.pigment-print.com        |
|                 ( unvollendet )                 |

Re: How Many Shades of Gray - K7 vs K3?

2011-03-23 by hflockwood

Very BIG SNIP, small question:


> To answer your question about how QTR works.  On the Mac if you send QTR the
> 16-bit data (check 16-bit in PS and in QTR), QTR will linearly interpolate the
> values from the .quad file between 128 and 129.  On PCs or Mac where you don't
> set 16-bit, it'll work like the second case above.  Note that the 16 to 8 bit
> conversion has to be done intelligently -- PS and QTR both do this.
> 
> Try this out.  It's really worth seeing for yourself.
>  
> Roy

Roy,

On a Mac, how does one choose 16 bit in QTR?

Harry

Re: How Many Shades of Gray - K7 vs K3?

2011-03-23 by Roy

In the QTR print dialog the top pull down has QTR 8-bit, QTR 16-bit, and Calib Mode.

You also need to make sure the program you are printing from sends 16-bit.
In Photoshop CS5 there's a Send 16-bit Data on the preview page.   In CS4 its
hidden under Color Management pulldown:  select Output and see a 16-bit checkbox.
To set these the file has to be 16-bit and you have to have a QTR printer selected.
LR 3 has a 16-bit output in the Print section.  I'm not sure about Aperture.   All
other standard Mac apps don't send 16-bit as far as I know.

You need to be careful that you make all these selections to ensure real 16-bit.
Do all 16 or all 8 -- don't mix. 

Roy

--- In DigitalBlackandWhiteThePrint@yahoogroups.com, "hflockwood" <hflockwood@...> wrote:
Show quoted textHide quoted text
>
> 
> 
> Very BIG SNIP, small question:
> 
> 
> > To answer your question about how QTR works.  On the Mac if you send QTR the
> > 16-bit data (check 16-bit in PS and in QTR), QTR will linearly interpolate the
> > values from the .quad file between 128 and 129.  On PCs or Mac where you don't
> > set 16-bit, it'll work like the second case above.  Note that the 16 to 8 bit
> > conversion has to be done intelligently -- PS and QTR both do this.
> > 
> > Try this out.  It's really worth seeing for yourself.
> >  
> > Roy
> 
> Roy,
> 
> On a Mac, how does one choose 16 bit in QTR?
> 
> Harry
>

Re: How Many Shades of Gray - K7 vs K3?

2011-03-24 by hflockwood

I'm still inCS3; it appears that that choice is not available.

Harry

--- In DigitalBlackandWhiteThePrint@yahoogroups.com, "Roy" <roy@...> wrote:
Show quoted textHide quoted text
>
> In the QTR print dialog the top pull down has QTR 8-bit, QTR 16-bit, and Calib Mode.
> 
> You also need to make sure the program you are printing from sends 16-bit.
> In Photoshop CS5 there's a Send 16-bit Data on the preview page.   In CS4 its
> hidden under Color Management pulldown:  select Output and see a 16-bit checkbox.
> To set these the file has to be 16-bit and you have to have a QTR printer selected.
> LR 3 has a 16-bit output in the Print section.  I'm not sure about Aperture.   All
> other standard Mac apps don't send 16-bit as far as I know.
> 
> You need to be careful that you make all these selections to ensure real 16-bit.
> Do all 16 or all 8 -- don't mix. 
> 
> Roy
> 
> --- In DigitalBlackandWhiteThePrint@yahoogroups.com, "hflockwood" <hflockwood@> wrote:
> >
> > 
> > 
> > Very BIG SNIP, small question:
> > 
> > 
> > > To answer your question about how QTR works.  On the Mac if you send QTR the
> > > 16-bit data (check 16-bit in PS and in QTR), QTR will linearly interpolate the
> > > values from the .quad file between 128 and 129.  On PCs or Mac where you don't
> > > set 16-bit, it'll work like the second case above.  Note that the 16 to 8 bit
> > > conversion has to be done intelligently -- PS and QTR both do this.
> > > 
> > > Try this out.  It's really worth seeing for yourself.
> > >  
> > > Roy
> > 
> > Roy,
> > 
> > On a Mac, how does one choose 16 bit in QTR?
> > 
> > Harry
> >
>

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