Photoshop jpg overhead?

I'm trying to save a thumbnail of an image at 50x75 pixels as a jpg. Some of the images that have been supplied to me already have these thumbnails, weighing in at 4kb. When I try to save similar from Photoshop, the lowest I can get is 20kb. (Yes, I have turned off the option to save a preview image) Is there some other optional overhead that PS is including or what? I'm on a mac by the way, on CS1.

"Save for web" and choose your "compression options" as needed.

Brilliant! Thanks a lot. I love Photoshop, I've been using it for years and consider myself a fairly adept user, but there's still loads I haven't even touched.

I notice that it takes up 4kb on disk even though it's only 1736 bytes. Is that the smallest disk space you can take up on HFS+ ?

Puh i've no idea but i guess yes...shouldn't it also tell you the real size which is occupied in the "container" via information?

Photoshop still bloats .jpg images, I always optimise them before use with Macromedia Fireworks.

Yep, Fireworks (when will it be killed?) is great for this but you can also just use a jpg-plugin for photoshop like you would do for jp2...

newer versions of photoshop come with image ready that do more optimized images. Somehow loading an image in 3DSmax and saving again beats everyone elses file size, whether its PNG, JPG etc.

For those who just have enough time: Start a competition! Someone provides a set of pngs (different sizes) and the people would have to compress it at high(=60) quality and then you take a look at the filesizes... *lol*... ;O)