Digital BW, The Print

Now I'm confused too.  Since I am not an expert in the "dot" area, I
have to defer to the book, "Making Digital Negatives for Contact
Printing" by Dan Burkholder (pg 36).  His definition of stachastic
(Random Dot) images is:

"Negatives that vary the dot "frequency" are called stochastic
negatives. Instead of arranging the spots of ink like so many soldiers
in formation, stochastic negatives use much smaller specks that are
randomly arranged, much like the grain in conventional film.  By
varying the concentration of these tiny specks, the shades of gray are
simulated."

Dan Burkholder goes on to talk about two kinds of Random dot images
that he uses, which are (1)Diffusion dither bitmaps made in Photoshop,
and (2)Icefields stachastic images (from a stand-alone program).

I'm only assuming that if you don't use the Diffusion dither bitmaps
SPECIFICALLY in Photoshop you're going to get virtually Halftone dot
images from your jpeg or tiff or photoshop files, and the printer
drivers take it from there.

I don't worry about Diffusion dither bitmaps because I know that the
Piezography driver on my Epson will take care of the straight dot
output that I send it.  I also know that Epson has its own stochastic
method, but don't know what it is (other than it uses piezoelectric
principles to make ink dots of variable size). 

I do know that I have NEVER seen the term Halftone used without
meaning LINE (or grid) Screen. I also know that you can specify
Halftone in the Epson printer setup, but I have only ever used it to
make print screens for photo-intaglio printmaking where I wanted the grid.

Anybody know anything more?
Thanks,
Cathy



--- In DigitalBlackandWhiteThePrint@y..., Carolyn  Frayn
<carolyn@u...> wrote:
> Dear Austin,
> 
> My understanding is that halftone is limited to a grid pattern...
Stochastic
> is not. 
> 
> Stochastic printing does not use a grid as halftone does, that is
why it can
> achieve smoother prints, it is random, there are no rosettes
patterns.  I
> also understand that lpi is not applicable to stochastic printing.
> 
> I'm confused by some of your comments regarding halftoning. You have
give me
> the impression that an inkjet printer uses halftoning to print. I don't
> agree, an inkjet printer uses a stochastic approach, a dither, random
> placement of dots in different densities.  Maybe I misunderstood your
> postings... wouldn't be the first time. :-)
> 
> Carolyn
> 
> 
> 
> > You can use a stochastic pattern, that does not mean it isn't a
halftone.
> > Halftone is a technique, and many different methodologies can be
used to
> > achieve this technique.
> > 
> > A halftone is not limited to a grid pattern.