For optimizing your webpage use the alt tag to accurately describe the each image, and include descriptive content around each image. if the image is not used in context, you should add a couple of lines below the image describing it. At the very least, images should contain alt tags with one or two keywords describing that image, and you should try surrounding that image with relevant text.
Images make your sites attractive for getting user attention. Many visitors do not like reading all specified content on our site so for those users you can use images with appropriate alt tag with sort description. Search engine also include data of images in their database. So you can find images in search engine's database.
You should always use simple, clear and light images. Always use small size images in your website. Large image can increase website loading times .And always add alt tag on your images for image optimization.