To optimize an image for the search engines. Just name the image file with the relevant/descriptive name and insert the Alt attribute with a information regarding the image in the Image HTML code. This will help search engines to crawl and capture the images along with the information provided by you in the alt attributes and in the file name. This will be helping us in getting some web traffic from the image search.
Aforementioned are on-page optimization do create image sitemap and submit it to GWT, along with that do share you images through image sharing sites, tagging with your keyword. Share it through social media sites, forums etc asking your friends/experts for a feedback etc.
Image Optimization is important because it help to notice Search Engine what is the image content about. That is why people try to describe the image in ALT tag with keywords and title of the image may not that important. All you need is set ALT for every image sometime even link and button do have ALT as well.
If using wordpress, just install this free plugin _http://wordpress.org/extend/plugins/seo-image/ It work great.
Image Optimization = ALT + IMG Tag= use keywords Google crawler not read your Image so we use keywords in alt tag for image optimization.
Here are the some tips for image optimizaton :- 1)use your primary keyword in image title. 2)use your main keyword in alt text. 3)always use alt text in image of your site. for ex:- <img src="image url" alt="text"> 4)share your image in image sharing sites like flickr, photobucket etc. 5)share your image in social networking sites like pinterest, facebook, twitter etc. 6)create a sitemap for your image. Hope these tips are useful for u........