eps versus jpg

[Melanie Gross]

Hi,
 
I inserted two images side by side and this works fine as long I insert
two eps-files. If I want to insert an eps- and a jpg-file the jpg-image
looks much smaller than the eps although both columns are sized 50% and
the images within their columns are sized 100%. The jpg-file seems to
have a white frame around it. I exported both images from matlab
graphics, does the problem come from exporting and can I work around it
in Lyx?
 
Thank you,
Melanie