RE: filmscanners: dither vs haltoning (was File sizes, file formats, etc. for printing 8.5 x 11and 13 x 17...

["Austin Franklin" <austin@darkroom.com>]

>     "Halftoning" really has nothing to do with digital imaging ...

I completely disagree.  Halftone is a process, and is implementation
independent.

> But in the context of consumer, and pro-sumer inkjet
> printing, halftoning is not the process used, rather a mixture of
> finer dots ... dots as fine as possible ... what I describe as
> "dithering".

Both my Epson printers (3000 and 1160) have a 'halftone' setting, as well as
my QMS laser printer...so both of them certainly believe they are
'halftoning'.  As I said, halftoning is a process that is implementation
independent.  The way 'halftoning' is done in a digital printer, typically,
is to create a halftone cell, which is an x by y group of printer dots.  You
vary the number of dots that are on, and that pattern to create the
halftone.

I'm a little miffed...I've designed digital imaging systems for 20 years,
and amongst the equipment I designed was for Imagitex, and was a digital
halftone pre-press system.  The term has always been halftoning in my
book...and I am curious how the term 'dithering' came to 'seemingly' replace
it.  Dithering, as I posted earlier, is something different.  It is
different than halftoning, and certainly can be used in an implementation of
halftoning...

Do you have any references that support the term 'dithering' as the PROCESS,
not a method/implementation, but the process?  I am interested in getting to
the bottom of this terminology 'misunderstanding'.

I am certainly not saying you are wrong, but I must say if you are right,
someone re-wrote the definitions of halftone and dither, and forgot to tell
Epson, QMS and Adobe about it, oh, and me too ;-)

Here is the first part of the definition of halftone from PS help:

"Halftoning: To create the illusion of continuous tones when printed, images
are broken down into a series of dots. This process is called halftoning."

Which is clearly implementation independent, and does not specify digital or
analog.  It goes on to say:

"Varying the sizes of the dots in a halftone screen creates the optical
illusion of variations of gray or continuous color in the image."

That, IMO, is an example of an implementation...to vary the size of the
dots.  I believe other implementations still are halftoning, but not
necessarily using varying dot sizes, but varying number of dots per unit
area...still to the same end, breaking down the image into a series of
dots...

The halftone, IMO, is a brilliant process.