Digital BW, The Print

Hi Roy,

> >
> > > > That is the one I thought you were using when you did your
> measurements
> > > > (21step)...but that's not a 256 step wedge.  What's the 256
> > > step wedge you
> > > > are referring to?
> > >
> > > Well a gradient in 8-bit is just the same as a 256 step wedge.
> >
> > Doesn't that depend on how it's made?  A step wedge typically
> has defined
> > squares...and a gradient doesn't necessarily...but it does
> makes sense that
> > it would be made that way.
>
> Yes, using the gradient tool without dithering will make squares,
> with dithering
> it will actually smooth between transition.

Oh, you mean PS dithering, not Piezo driver dithering...right?

> >
> > I believe the flush image may be a far better data source, if
> it is in fact
> > a 256 step wedge...and since I can't get PS to display
> grayscale in tonal
> > values, it's hard to test out.  You don't happen to know how to
> get PS to
> > display the actually pixel values...not just the %, which only gives me
> > discernability to %1...
>
> I see Tyler has already mentioned the RGB way to look.  Its also
> unfortunate
> that you can never see the low bits in 16 bit mode.

Agreed!

> Recently someone mentioned that PS only uses
> 15 bits in high bit mode, I was able to confirm this using this method.

I've never done anything in PS in 16 bit mode, but using 15 bits is just not
kosher in my book.

> > > It not labeled
> > > as such but it does have all 256 levels (some do appear to be
> doubled) and
> > > far as I can tell there's no dithering between levels.
> >
> > But if there's no dithering between the levels...then doesn't
> that refute
> > the 1000 tone claim...and support the less than 256 claim?
>
> As I said above, the dithering/no-dithering gives you the steps versus
> smooth transition.  I'd hope you could try both and see the results.

Hum...if it's PS that's dithering...I wonder what the driver will do with it
already dithered...

> >
> > > >
> > > > BTW, do Rourke's "curves" print "more than 1000 tones" also?
> > >
> > > No real idea, but it is a more difficult question because there
> > > are so many
> > > different curves and they were all hand done and were somewhat limited
> > > by the max number of points in a PS curves.
> >
> > I'm not quite sure what PS curves have to do with it...  Isn't the data
>
> Its just that PS limits how accurate you can specify the adjustment curve.

Understood.  I still don't know how the printer driver etc. handles the
Rourke output methodology though...

> > still sent to the printer driver, which only handles 8 bits
> anyway...but I
> > guess if it is in fact printing 8 bits/channel (and in this case, it
> > actually is), you could theoretically get the additional tones
> (though it
> > isn't 256 x 4 BTW, since you can't print all the way to %100
> with three of
> > the inks...and some tones would be duplicated etc....which,
> this argument,
> > in and of it self, also brings me to question Cone's claim...since you'd
> > have to get 512 of the tones from the black ink only etc.).

What did you think of the above paragraph?

Regards,

Austin