What we did for the non-tech people was simply tell them to always use setting #6 on photoshop and use the progressive setting. Two steps seemed the most they could handle.

http://i.imgur.com/vct3D.png (best one-shot photoshop settings for web jpegs)

I had to go into photoshop and save the same image repeatedly under all the different settings and then examine the resulting jpeg under different tools to see exactly what it was doing.

It also doesn't help that photoshop bloats jpegs by adding hidden adobe meta to every jpeg (beyond and different from exif).

Here is a technical analysis someone did on the photoshop settings:

http://www.impulseadventure.com/photo/jpeg-quantization.html...

I believe if you use "Save for Web", it will strip out most metadata and EXIF from the image before saving. Here's a result of using "Save for Web" (1.jpg), passing through JPEGTRAN with `-copy none -optimize` (2.jpg) and `JFIFREMOVE` (3.jpg):

    330090  1.jpg
    329916  2.jpg
    329898  3.jpg

It can also do a lossless conversion to progressive format.

Most people do not know about it though. JPEGOPTIM is another one.

You can examine what's embedded in the image here http://regex.info/exif.cgi

but there are better offline tools.

* It sounds great in theory but the previous example only saved < 200 bytes. That's not really optimization, that's overkill.*

That's a fair point, but if you've got a site that's getting hundreds of thousands or millions of views, or a large number of thumbnails, the one-time effort to shrink image size might be worth it.

Web designers don't "Save" web images, they use "Save for Web" which strips out the extras.