Digital BW, The Print

Anthony, you wrote,

> Ernst writes:
>
> > The real resolution is usually 720 dpi
> > while some go up to 1440.
>
> The only resolution that interests me is pixels per inch, and that's
nowhere
> near 720 ppi.  If it is even 200 ppi, I'd be surprised.  I can easily see
> the masses of ink dots under a loupe, and even with the naked eye.

Depending on what you want to reproduce an Epson printer with a true 720 dpi
resolution will require 720 ppi down to 180 ppi input. 720 dpi for vector
art, fonts that are converted to bitmaps and so the contour definition still
gains up to the true printer resolution. And even then the tricks of
shifting a dotrow works for a quality improvement. For photos and colour
only, the input required is based on a consensus among users. The older
models didn't improve much above 240 ppi input. With the latest consumer
models (claimed) 2880 dpi, 3 picolitre smallest size droplet, 3 droplet
sizes per chosen resolution, CcMmYK it wouldn't surprise me if 720 dpi input
shows an improvement above 480 dpi on the best papers. Whether that still
can be seen with the naked eye is something else. Let us compare that with
offset printing and let us take the worst relation ppi/lpi of 2. 480 then
translates to 240 lpi offset raster, 720 translates to 360 lpi. If we take
the best translation ppi/lpi 1.41, then the numbers are 340 lpi and 510 lpi
resp. They all go beyond what is usual for good offset raster screening =160
lpi and one even above extremes like 500 lines per inch as has been used by
some offset printers to show their capability. Whether the last is an
economic and technical sound process is another matter, Epsons can do it any
time of the day. Then there's the far better gamut of Epson dyes and for
that matter Ilford dyes (Wide Spectrum inks being a klone of the last). The
9600/7600/2200 pigment inks have a better gamut than offset inks as well.

The translation of input ppi through printer dpi and what you observe then
in the print and give a quality expressed in subjective ppi's is another
matter. Like in any reproduction process there's a loss. You can only
compare it with other print processes and then inkjet is getting near the
top. The nice thing is that it is also very versatile from textile
sublimation to digital cibachrome on the same hardware.

> > You should examine the small sized inkjet
> > prints and the latests wide format models
> > of Epson and then the conclusion can only
> > be that they exceed offset quality.
>
> They must be _very_ recent, because nothing I've seen up to now has been
> that good.

The wide format 9600/7600 are now delivered, some have them running for 2
months now.
The consumer models with dye inks that have that quality are at least a year
old.

> > Your 2000p is one of few mistakes in printer
> > models that Epson launched. It would perform
> > far better with dye inks.
>
> Except that the resulting prints would be useless after six months.  A
nice
> print that only lasts for a few months isn't much better than a long-term
> print with metamerism.

20 years with the right dyes and papers. Better than most conventional photo
prints and most offset printed material. I wonder what ink the new HP
printers use as HP claims an even longer (Wilhelm tested) fade resistance,
most likely pigment but maybe ........

Ernst