File compression

hi, i haf a question.

Say i have a jpeg which is only 17kb and a png at 247kb.

Both files have similar document size,resolution and etc. Just different file format.

I import both files into flash and create only 1 keyframe. No animations just still image.

When saved as jpeg.fla, the file size is 144kb and the png.fla is only 57kb. When i publish both flas, both have the same size which is only 17kb. Why is this so? It’s kinda confusing cause you have a small jpeg but it generates big fla size while u have a big png and it generates a smaller fla size.

How do u actually maintain quality and at the same generate a smaller swf file? and what is the best file compression to use? jpg?gif?bmp?png? ohhh confusing. Appreciate if someone could answer this. Thanks a lot, haf a good day.