What is most SEO optimized image HTML code for?

Question

so far i was doing it like this:

<a href="http://domain.com" title="Keyword"><img src="image.png" alt="Keyword" /></a>

Now, i discovered that images can have title attribute too:

<a href="http://domain.com" title="Keyword"><img src="image.png" alt="Keyword" title="Keyword"/></a>

Is there any other optimization i could pull off to boost image links value?

Answer 1

I think that's the best you can do really, someone told me to try and make image names as descriptive as possible, for instance:

image_001.jpg --> honda_accord_2009.jpg

Granted image.png is just an example, but it might apply.

That's all I could think of.