Rajan,
Very first time when i saw a
thread on size-i came to know size limit is 1 MB - when people have to upload the assignment.
Somebody from Oracle should intervene here and tell the size limit. When I was in Oracle-my email Id cannot accept the attachments more than 5 MB so i assume if you have to send the assignment as part email attachment - it should not go beyond 5 MB. But in case you are uploading it-it can go beyond 5 MB but i am not sure what is the size limit now?
Please go thru my blog-convert your images into PNG. I have provided some tips to reduce the size of the images. Overall JAR file should not go beyond 2 MB-that's what i feel.