If you are trying to get maximum traffic to your website,getting the images in your website indexed by google is an effective option.You may be wondering why you are not getting enough visitors from search engine even though,you have good page rank in google and all your pages are indexed by google.I must say its much more easier to get listed in google image search than in google page search.Suppose if your image got ranked well for a particular key word and you got some visitors through image search,then obviously,the rank of the page or the post which contains the searched imaged will also increase.So my point is try to include as many images as possible in your post and optimise for google image search,your post also will get indexed well slowly.I will tell some tips to optimise images in your website.

1. Search engines can only track content through text,not images.So add a text description to each image by using alt tags.
2 . In Google Webmaster Tools, enable enhanced image search

3 . Rename the images and include the keyword you are trying to optimise for that image separated by ‘-’
4 .Surround the image with text that is relevant and contains the name of the image.
5 . The larger the dimension of the image,greater the chancre of getting ranked well by google

See this video .The image optimization is explained well in this