We just finished the body text optimization with the previous tutorial Keyword Proximity and phrase order.
There are few steps left to complete your on-page optimization.

Next in the list is:

Image Optimization advices

Most people think that the images cannot be optimized well, and they are NOT so far from the truth!

The reason of that is because the images are not in the search engines power to be revealed what they contain.

I am sure if you have an e-mail, there are thousands of e-mails received with content like:

“Hi John, the last trip was awesome ... blah blah..” and a picture attached is totally different, offering pills that make your live better.
Simply the e-mail spam filters are week to catch them even the best of them are using OSR as well as the biggest search engines.

Here is one “optimized image” with the text :

This is part of our inbox. I have put blur effect on the data as I am no aware when the SE will manage to OSR the text and consider this page as bad.

Well then, what the search engines understand from a published image? Let’s see:

Image ALT text

Alt comes from Alternative, and alt text has purpose to describe the image you have placed. This heading “ALT text” comes from the time of non-graphics operating systems when your browser can’t display an image the alt text is used in place of the image.

The text here should be explicative but short, and you can use your targeted keywords as an alt text (only if it is not a link!).
In web link if an image as an anchor, the ALT behaves as an anchor text. Then there is some importance for the page optimization.

Here is an example how alternative text looks in the code:

Image file name

Names of the image files should be also meaningful according to what they effigy. Use names like “raving-rabbits.jpg” instead of “PIC23485.jpg”. You may keep the file name of the same to the ALT text.

Image Title

Title of an image is a little tool tip box showing on the image, when you move your mouse over it. See the image bellow to get an idea.

Image Linking

Whenever you want to link an image, use a keyword that explains it. For example: if I use the above image I will put the keyword “pigeon”. If I put “click here” that will not tell much to the search engines about it, and SE like images.google.com probably never will list it in a search.

That is the general image optimization.
The next tutorial will be about Internal links navigation.