Andre, a 300% upsize of those JPEGs is pretty drastic. You might be able to get away with it...
The RAW files are less of a problem. I save them as TIFFs, then re-size those if necessary, carefully following the guidelines of the stock image library etc.
QUOTE (spi4u2 @ Apr 22 2008, 08:56 PM)

QUOTE (markgoldstein @ Apr 22 2008, 12:08 PM)

How big are your original source images?
Photoshop CS3 is much better at doing enlargements than previous versions, so depending on your specific needs, it may be good enough.
I have some jpeg files that are about 1500 by 1000 pixels that I would like to upsize to about 6000 by 4000. I also have files that are raw that are approximately 6000 by 4000 that I would like to upsize so that they can be used for posters, large pictures, or even billboards if at all possible. Most of what I have I want to upsize as much as possible so that I have more choices available for the stock photography market.
Thank you for your time in ansering my questions.
Andre