AW: Line width in inported graphics slightly diminishing in FM generated PDFs

[Reng, Winfried]

Hi,

> >We're using Acrobat's preflight feature to check for lines 
> thinner than
> >0.2 pts. The thinnest lines in our .eps graphics are exactly 0.2 pts,
> >but when we import these graphics in FM and check the PDFs 
> created from
> >FM, Acrobat preflight says the graphics uses "0.199600pt" lines.
> >
> >PDFs of these individual graphics, created from Illustrator, do not
> >have problems with Acrobat prefight, so it seems to be some 
> sort of FM
> >conversion problem.
> >
> >Why does this happen, and is there any way to prevent this on the FM
> >side? If there is no way to fix this, we'd have to tell our 
> illustrator
> >to make the lines in the graphics slightly thicker.
> 
> This looks a lot like a rounding error problem due to two 
> different applications using different precision math. In 
> floating-point math, computers use a set number of bits to 
> represent the complete range of natural numbers. As a result, 
> some numbers actually cannot be represented precisely: the 
> more bits you use, the closer you get, but there's always a 
> compromise.

When I check the font size in my PDF files there´s also often a
difference. E.g. the font size in FrameMaker is 10 pt, and Acrobat
says 9.96 pt. (Other text in Acrobat has exactly the same font size
as in FrameMaker.) 4 % would be a rather large rounding error.
I don´t know whether these differences in line width and font size
have the same cause.

Best regards

Winfried