[R] PowerPoint

Philipp Pagel philipp.pagel.lists at t-online.de
Fri Jun 23 19:39:58 CEST 2006

On Fri, Jun 23, 2006 at 11:27:00AM -0500, Marc Schwartz (via MN) wrote:
> On Fri, 2006-06-23 at 18:16 +0200, Philipp Pagel wrote:
> > On Fri, Jun 23, 2006 at 09:21:37AM -0400, Gabor Grothendieck wrote:
> > > Note that jpg, bmp and png are in less desirable bit mapped formats whereas
> > > eps is in a more desirable vector format (magnification and shrinking does
> > > not involve loss of info) and so would be preferable from a quality
> > > viewpoint.
> > 
> > In addition to seconding the above statement I'd like to add that in
> > cases where you are forced to use a bitmap format png tends to produce
> > much better results than jpg where line drawings (e.g. most plots) are
> > concerned. JPG format on the other hand is great for anyting which can be
> > discirbed as photography-like. jpg images of plots tend to suffer from
> > bad artifacts...

> That is generally because png files are not compressed, whereas jpg
> files are. 

In fact, png uses a combination of pre-filtering and lossless compression 
(in contrast to lossy compression algortihms use in jpg). 

Of course, lossy compression can achieve much smaller file sizes for
most images. While even a substantial loss of information can go
undetected by the observer in the case of photographic images with no
sharp edges, line drawings suffer badly. 

Line drawings usually contain vast percentages of empty space (i.e.
white) and thus can be compressed quite effectively by the
pre-filteing/lossless compression used by png.

Anyway - I totally agree that eps rules and pixel formats should be
avoided at all cost for illustrations, plots, etc. ...


Dr. Philipp Pagel                            Tel.  +49-8161-71 2131
Dept. of Genome Oriented Bioinformatics      Fax.  +49-8161-71 2186
Technical University of Munich
Science Center Weihenstephan
85350 Freising, Germany


Institute for Bioinformatics / MIPS          Tel.  +49-89-3187 3675
GSF - National Research Center               Fax.  +49-89-3187 3585
      for Environment and Health
Ingolstädter Landstrasse 1
85764 Neuherberg, Germany

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