Digital BW, The Print

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