Optimize your images in the following ways:
* Keywords in alt text, text around the image, image name, page title;
* Preferred image formatting - jpg;
* Separate SE accessible image folder;
* Image freshness.
* Enabled image search option at Google webmaster tool.
* Reasonable image file size
* Limited number of images per page
* Popular and reliable photo sharing hosting.
It is better to have the reasonable size of the images to improve the speed of the website