Digital BW, The Print

Ernst,

The tests you give the link to are subtly different from the ones I
did because they involve sending a file to the printer at only one ppi
value (720 ppi, according to the instructions). As such they do not
represent true comparisons between, say, 360 ppi and 720 ppi. To
assess 360 ppi you have to send a true 360 ppi file to the printer,
not a 720 ppi file with pseudo-360 ppi data in it. 

By sending checkerboard and lines to the printer at different ppi
values you can see how the driver maps pixels to the matrix produced
by the print heads. 

Best,
Helen
 
--- In DigitalBlackandWhiteThePrint@yahoogroups.com, Ernst Dinkla
<E.Dinkla@...> wrote:
>
> Helen Bach wrote:
> > I printed a checkerboard of one pixel squares and sets of lines one
> > pixel wide at 1440, 720, 360, 300 and 288 ppi using the Epson driver
> > and OPM on two different 2200s loaded with glossy paper.
> > 
> > With the Epson driver at the 1440 and 2880 dpi settings the only print
> > that was free of artefacts was the one made at 288 ppi. The 360 ppi
> > was close, and the definition of the lines was very good. At higher
> > ppi the checkerboard and lines were not well defined.
> > 
> > With OPM the 360 ppi print had the fewest artefacts, but none were
> > artefact-free. Moire-like lines were evident on all the prints, but
> > least noticeable at 360 ppi. The definition was also best at 360 ppi.
> > At higher ppi the checkerboard was not properly defined. 
> > 
> > There appears to be a difference between the 'native' horizontal and
> > vertical resolution.
> > 
> > If the test patch had been too small, all the artefacts would not have
> > been evident. The test patches were one inch square at 360 ppi.
> > 
> > Best,
> > Helen 
> 
> 
> This page describes some test methods that may be more 
> suitable for photographic images:
> 
> http://www.ddisoftware.com/qimage/quality/
> 
> 
> Ernst
> 
>                     --
>            Ernst Dinkla
> 
> 
> www.pigment-print.com
> (         unvollendet         )
>