Digital BW, The Print

> Austin -- The mere fact that some prints have more tones than others
> doesn't have anything to do with the dynamic range of the medium
> (digital inks on paper) does it?

It very well may, but it may also be just how it was printed...

> Don't we have to distinguish between the dynamic range in the digital
> image itself (i.e., in its electronic form) and the dynamic range of
> the analog image that gets printed by a digital system?

Not really, providing both are larger than the print medium.

> For example,
> a black and white digital image may be composed of four different
> tones (in the computer) and when it's printed the image on the paper
> displays four different tones.  But that doesn't tell you anything
> about the dynamic range of the printing process (i.e., the
> combination of printer driver, digital printer, ink, and paper).

That is very true, and that is why I have said you have to separate the
dynamic range of the image with the dynamic range of the system.

> For that you'd need to get an electronic image that itself had more
> tones than could be distinguished in the image of it that gets
> printed, AND you'd have to compare the two and see that the printed
> image doesn't have as many tones as were present in its electronic
> representation. Then you'd know that the paper/printing process had
> lower dynamic range than what was present in the electronic image.

Correct.

> Isn't this related to the process of calibrating our printers with
> 256 step wedges, making sure that each of the tones is
> distinguishable from the rest AND THUS maximizing the dynamic range
> of the printing system?

Yes.

> We can't tell whether the dynamic range of a
> printing system is low just because we see an image it printed that
> has low dynamic range (the source image might be the link with the
> low dynamic range).

But...if we print the same negative with two systems, and one has visibly
more tones than the other, then I believe we can say, in a general way, that
one has a higher dynamic range than the other.  The right thing to do to
really get to the bottom of this is get a test film that has 256 tones on
it, and see if both systems (wet and digital) can print it...  To avoid the
scanner issue, you could always do a 256 step wedge in PS, and send it
directly to the printer.

> But we can tell that a system has high dynamic
> range if we see an image printed by it that has subtle gradations in
> tone (dynamic range is at least as great as what's observed in the
> printed image).

Yes.

> Question:  assuming that we can calibrate digital printers to
> distinguish between the 256 shades of gray in a step image, how much
> more dynamic range is there in them?

You lost me, as I don't know what you're comparing it to.

> We can use source images with
> up to 2^16 shades of gray in Photoshop (what is that, 65536
> shades?).  Can any of the print drivers make use of the extra bits?

It has been said on the Piezo list that the PiezoPro/V6 uses 16 bit images,
and takes advantage of the additional bits...and people have said they
noticed improved tonality.  I have not seen that first hand...  I do have my
reservations on that claim though...given our eye limitations...

Regards,

Austin