Digital BW, The Print

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
>
>  
>


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