Since search engines spiders can not crawl very well an image, there are several SEO techniques used to help spiders understand an image :
- use "alt" attribute to describe images;
- use descriptive names when saving images;
- set the width and height of an image;
- use a low number of images on a page or resize them to obtain a smaller image in size
User experience matters for search engines, so having many images on a web page may slowdown a website and the user may wait longer to view the content. Resizing images may increase the website speed.