Hi,
CVI does not have any built in functions to read or write jpeg files, it is on our wish list. As Philippe pointed out here, the web site contains a very good fp with a nice set of functions to read and write jpeg files.
If you feel that CVI should support JPEG files you can support our cause by going to www.ni.com/contact and submit this request under product feedback.
Good luck!
Regards,
Juan Carlos
N.I.