Digital BW, The Print

I think its very much like a moire pattern or aliasing.  All the Epson drivers
effectively resample the image to 360 or 720 ppi.  With a straight diagonal
line its likely you would see a jagged pattern of aliasing.  Exact multiples of 
360 or completely odd numbers would be probably be all right.  The 301
may be slightly jagged but won't have a pattern in it so your eye doesn't
object to it.

Roy

--- In DigitalBlackandWhiteThePrint@yahoogroups.com, "Steve Gledhill" 
<stephengledhill@y...> wrote:
> Lotusm50,
> I think the problem that I described to start this thread is only
> apparent when your chosen ppi is some simple fraction of 360ppi - as
> is 300ppi.  When the ppi is some odd number like 327ppi or 941 ppi or
> perhaps as suggested earlier in this thread 301ppi or 299ppi then the
> maths involved in the driver resampling to the native printer
> resolution (360 ppi / 720 ppi / ...) doesn't give rise to the 'jagged'
> effects that I described.
> 
> So, I believe the answer to your question is "no".  You can print any
> file at any ppi without the jaggies problem - as long as your file
> isn't a simple fraction of 360ppi - like the 300ppi where I found my
> problem.  You, like many people, may have never seen this problem, but
> those who print 300ppi files should look carefully - you my find a
> step improvement in your printing by the simple action of resampling
> to 360ppi before printing.
> 
> Steve
> http://www.virtuallygrey.co.uk/
> 
> --- In DigitalBlackandWhiteThePrint@yahoogroups.com, "Lotusm50"
> <LotusM50@s...> wrote:
> > What I don't get is, does this mean that you can really optimally
> > print only 4 or 5 different sized prints for a given file.  Say with a
> > given file you can print an 8x10 print at 720 ppi.  Then say you want
> > to crop it differently leaving the file smaller by 15%.  Does that
> > mean you can't print the file at the 8x10 size because it would no
> > longer print at 720 ppi (or 360 ppi)?  Or odes the printer dricer
> > automatically re-size file sent ot the printer to the optimal
> > resultion for the printer.  It would seem quite odd to me that a
> > proffessional quality printer would be so limited in effective print
> > sizes.  Or is the quality difference between printing at 360 ppi and
> > 320 ppi in fact almost impossible to see?  I don't think I ever try to
> > print at 360 or 720 ppi.  I take the file as it comes and if I want an
> > 8x10 or an 11x14 I print it to that size (using 1160 with CIS &
> > Piezotone inks).  I never really see any problems with the resolution,
> > detail, or quality of the print.
> > 
> > What shouls I be noticing in a print not printed at a multiple of 720
> > ppi that I am not seeing?
> > 
> > 
> > --- In DigitalBlackandWhiteThePrint@yahoogroups.com, "Bob Frost"
> > <bob@f...> wrote:
> > > Steve,
> > > 
> > > I haven't printed at some of those resolutions, but I always
> > understood that 
> > > the numbers should be factors of 720ppi, the ppi that the printer
> > uses for 
> > > printing, not the dpi. So 360ppi is OK, as is 240 and 180, but not
> > 480 or 
> > > 576. Easy to confirm by printing a set of black and white 1 pixel
> > lines and 
> > > looking for the aliasing patterns. Many give you a lovely 'tartan'
> like 
> > > print (for those of you who know of Scotland).
> > > 
> > > Bob Frost.
> > > 
> > > 
> > > ----- Original Message ----- 
> > > From: "Steve Kale" <stevekale@b...>
> > > 
> > > 
> > > I understood good practice to be at least always use a clean factor
> > of the
> > > print resolution ie 2880/4=720, 2880/5=576, 2880/6=480, 2880/8=360,
> > > 2880/9=320, 2880/10=288.  The 300 simply came about as a result of
> > the old
> > > 2x150lpi (as Bob Frost noted in an earlier post).