[magick-users] jpg to eps keeping all pixels

[Scott Spearman]

Because of the nature of EPS being PostScript, an EPS document doesn't
necessarily have a concept of "resolution" in a normal raster image way.
Many EPS documents are vector graphics, which are scaled to points, 72
points to an inch normally.

EPS does support raster graphics within an EPS file, but the resolution
there is completely arbitrary based on how the document is created.  In many
cases the image itself is drawn very small (I have a system that draws a 1x1
point image from a digital photo) and then scales it up by about 40x60 using
a simple PostScript scale.

My best suggestion would be to look through the header of the EPS for a
bounding box (all EPS files are required to have one) and then divide those
dimensions by 72 PPI (points per inch) to get your final resolution size.

Something that I also learned from the list is that you can do something
like set the density to 288x288, read the image, then resize it to 25%,
which should give you something of the appropriate size, and with better
quality than the original, but it cannot guarantee that you have a
pixel-per-pixel copy of the original.  It's just the nature of PostScript to
not handle raster data very nicely.

Scott Spearman

 

Programmer Analyst - Pikeville Medical Center

Scott.Spearman at pikevillehospital.org

(606) 218-4660


-----Original Message-----
From: magick-users-bounces at imagemagick.org
[mailto:magick-users-bounces at imagemagick.org] On Behalf Of Hugemann
Sent: Monday, January 01, 2007 1:18 PM
To: magick-users at imagemagick.org
Subject: Re: [magick-users] jpg to eps keeping all pixels

BTW: I have the inverse problem; I would like to convert hundreds of EPS 
files to JPEGs preserving all pixels, i.e the original resolution. Up to 
now, I could not figure out, how IM can automatically read the EPS 
resolution from the EPS file and use it during the conversion.

Any ideas?

Wolfgang Hugemann
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