You can just run Pngcrush[1] in a directory full of images, and it'll optimize 'em all. Trivially easy to automate.

1: https://secure.wikimedia.org/wikipedia/en/wiki/Pngcrush

pngout does an even better job. He got it to 3.54 kilobytes, but pngout got it to 2.9K.

For ultimate optimization do pngout, then optipng, then advpng - in that order! Each one sometimes reduces it even more than the one before, but only if you run them in that order.

As a side note, you don't need to use secure.wikimedia.org any more. Changing the protocol on any of the Wikimedia sites to HTTPS works fine and doesn't have any mixed content errors.

HTTPS Everywhere is still redirecting to secure.wikimedia.org, so that's probably where any remaining links there are coming from.

Do browsers use the color profile for displaying the image? If so, wouldn't this affect the appearance of the image?

Some do, some don't. In most cases it will end up being converted to sRGB, so you're better off doing that conversion yourself.

There is a test to check if your browsers support it. http://www.color.org/version4html.xalter Chrome has no support at all, which is annoying really.

Chrome seems to support that, based on latest Chrome on mac.

Chrome 15 on OSX Lion here. Doesn't work at all.

Latest chrome on windows 7 here doesn't.

Safari, Firefox, Opera and even IE uses and adheres to ICC profiles in images. No idea what Chrome or other browsers do.