[softwarelist] Re: Selecting thin lines in OPW documents

  • From: Clive Bonsall <C.Bonsall@xxxxxxxx>
  • To: davidpilling@xxxxxxxxxxxxx
  • Date: Thu, 17 Aug 2006 19:05:48 +0100

Martin Wuerthner wrote: 

In message <44E41631.3090603@xxxxxxxx>
          Clive Bonsall <C.Bonsall@xxxxxxxx> wrote:

Chris Johnson wrote:

There has been a lot of discussion over the years in various
maillists and newsgroups about the problems that sometimes ensue when
printing 'thin' lines on high resolution devices.

Do you have more details on this?  When I started my current DTP project
using OPW, I was inclined to go for a line width (in tables especially)
of 0.25pt. However, when the documents were converted to PDF using
Acrobat Distiller, the lines appeared (to my eye) "too thick".

What happens when you print the resulting PDF or zoom in when viewing it? 0.25pt is pretty thin, but at low magnifications it is likely to appear thicker on screen compared to other content because its width covers a lot less than one pixel, yet without anti-aliasing a width of one pixel is the thinnest that can be shown. If you zoom in, the accuracy of the displayed width will improve a lot. Printing has the same effect due to the higher resolution used. > Martin 

Sorry, I meant 0.25mm ...

What you and DP have described is observable using Acrobat Distiller and my HP LJ1220 printer. I created a single-page test document in OPW with lines of varying thickness, ranging from Thin to 0.5mm in increments of 0.05mm. I then printed the document to AD (resolution set to 600 dpi) and again with resolution 2400 dpi. Looking at the two PDFs side by side on screen (Dell 20" LCD, 1600x1200 32-bit mode), I could detect no difference in thickness between corresponding lines, not at 100% nor 400% magnification. "Thin" appeared just as thick on screen in the 2400dpi PDF as in the 600dpi PDF.

However, when the OPW documents and PDFs were printed on standard paper on the LJ1220, there was a noticeable difference between 600dpi and 1200 dpi printer settings. All lines appeared thinner and fainter at 1200 dpi, but especially the "thin" line. So I can well appreciate that at 2400 dpi (if I had a printer capable of that) a "thin" line might be all but invisible.

Judging from these results, I'd guess that a line thickness setting of 0.25mm would give acceptable results at 2400dpi.

I'm grateful to you and DP for taking the trouble to explain.
--
CB

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