Here’s how to optimize images for the web:
Name your images descriptively and in plain language.
Optimize your alt attributes carefully.
Choose your image dimensions and product angles wisely.
Reduce the file size of your images.
Choose the right file type.
Optimize your thumbnails.
Use image sitemaps.
Beware of decorative images.
Use caution when using content delivery networks (CDNs).
Test your images.
Image optimization is the process of defining your images properly with the help of alt texts so that search engines know about your images and help rank them higher in search results.
In SEO, image optimization is defined as the optimization of images according to the rules of search engines such as image file size, alt tags/text etc.