An important technique of search engine optimization is to describe you image which you are giving in your website. Many people ignore this point and loose the chance of getting top position in a search engine page result. According to search engine optimization methodology if you are including any image in your web page it is necessary to give its description along with image.
Note: Never forget to give a title of the image and an alt text. Alter text (search engine robots can not read the image so it will read the alt text for the image ) is an important issue for the search engine robots. See the image bellow and you will be clear about seo friendly images i.e. how to insert title, alt text and description for an image.