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

["shAf" <michael@shaffer.net>]

Austin writes ...


> >     I consider "dither" as the general term, which includes
> > "halftone".  "Halftone" would seem best applied to traditional
> > methods, and not include some of the newer techniques ... e.g.,
> > "random" or "stoichastic" dithering ... but that may be just me
:o)
> >
>
> Well, I asked because someone wanted to 'discuss' with me that
halftone is
> not the proper term, that dither was.  I've been in digital imaging
for over
> 20 years, and I believe halftone is still appropriate to call the
overall
> process...and dither is but one method employed in halftoning...so I
think
> you have it reversed...

    "Halftoning" really has nothing to do with digital imaging ... but
it has adapted like many other imaging methods.  Like you implied
several posts ago "Halftoning is the process of breaking down a
continuous tone image into solid spots of differing sizes to create
the illusion of transitioning grays or colors in a printed image."
It may be a matter of simplistic and archiac definition, but laser and
inkjet printers, are not capable of halftoning in the traditional
sense.  For them to create a large dot, or large diamonds, rather than
small, they must put smaller dots together to do the same thing ...
whereas traditional halftoning was a high contrast photographic
process, involving a continuous tone negative (the original), a
defocussed screen and a high contrast film (the halftone copy) ...
carried next to the screening process.
    In the context of Photoshop separations, and postscript printing
... yes, this can digitally reproduce "halftoning", and a modern
method of the technique ... indeed, it is a very special art to apply
larger/smaller shapes (diamonds, hearts, smiley faces, etc) to image
formation.  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".
    As to either being the general term ... I would only turn to their
capabilities and ask ...  "If an inkjet can halftone, but the halftone
process cannot dither, which is the more general term?"  Or, are we
mixing apples & oranges???

shAf  :o)