Re: OT: WMF drawings from Docutech 135PS have thin and missing lines

[Allen Schaaf <soundbyte@xxxxxxxxxxxxxxxxxxx>]

At 11:52 AM 3/7/02, eric.dunn@ca.transport.bombardier.com wrote:


>Not to take issue with DOV, but:
>
>Did you check the line width setting? We use WMFs and CGMs created from
>illustrations in AutoCAD.
>
>At first all seemed fine, until we printed and many line were too faint.
>Investigation showed that the AutoCAD drawings were not using any line 
>weights for many line types. So effectively these lines were zero width. 
>Looked fine on screen (1 pixel line width), looked acceptable in drafts 
>off office laser printers (1/300" or 1/600 line width), started to 
>disappear on final print (Docutech 1/1200" or 1/2400" line width).

Eric,

I'm not sure where you get your figures, but Xerox only claims 600 dpi for 
a 135, and the same for a 6100. But office printers like the 4050 and 4100 
can do 1200 dpi.

Or are you saying that because they can modulate the density of the dot 
this is equivalent to 1200 dpi? As far as I know this is not possible on 
laser printers of any kind as opposed to a monitor which does exactly that 
to get shades of gray

There is always a lot of confusion on this issue because halftones are 
measured in lines per inch. They approximate various grays by changing the 
percentage of the coverage of a "pixel" (I know this is not correct 
terminology but it works for our purposes.) so that the mix of white and 
black create various grays like a pointillist painting.

Each half tone dot needs to be ten pixels by ten pixels which can create 
the illusion of 101 steps from white to solid black as in litho printing it 
is either white or black with no shading except by sizing the black to the 
white. Depending on the quality of the toner this might be a Dmax of 2.5 to 
3.0 which makes the steps a little ragged.

I know when I get a manual printed on a docutech, the lines per inch is 
either 85 or 100 for halftones with 100 being most common.


Allen Schaaf
Technical writing
<soundbyte@sound-by-design.com>

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