[softwarelist] Re: Halftone scanning

In <URL:news:local.opro> on Wed 28 Nov, Tim Powys-Lybbe wrote:
> In message of 28 Nov, Dave Barnett <dave@xxxxxxxxxxxxxxxxx> wrote:
> 
> > In a recent message David Pilling <flist@xxxxxxxxxxxxxxxxxxx> wrote:
> 
> <snip>
> 
> > > Dan made a good point. Moire patterning can also be due to the
> > > monitor screen - the magnify tool in DPscan has a button "rational"
> > > which gets rid of such effects by displaying one image pixel per
> > > screen pixel.
> > > 
> > That has no effect.  Increasing dpi above 100 increases problem.  I am 
> > happy with results for this image.
> > 
> > OT ?   One thing that I have found for DPscan is that increasing the 
> > 'Next' bar on the Task display reduces the incidence of 'Type 5' 
> > errors.
> 
> I would expect that the above problem and resolution only applies to
> screen images.  When you print, there should be a significant
> improvements at 300 dpi compared to 100 dpi.   (Unless your printer is a
> dot-matrix and restricted to 80 or so dpi.)
> 

I usually scan at 150 dpi for a 600dpi printer and print with a half-tone
screen of 90 lpi or 65 lpi if the output is to be reduced on a
photocopier. If scanning for screen use I'd probably drop to 100 dpi or less. 

Anthony

-- 
ajh@xxxxxxxxxxxxxxxxx

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