There are three Major Key Points to consider in Search Engine Optimization (SEO) of Images
1. Adding Alt Tags
2. File Name
3. Adding a caption
4. File Size of images
1. How to add Alt Tags in images?
<img src="image1.jpg" alt="How to drive" />Example: Let's say you have a image by the name of "image1"and Alt tag is "How to drive". When Google will crawl images, it will not crawl image1 name, it will crawl Alt tag "How to drive".
So Adding Alt tag is so important for optimizing images for better search engine ranking.
2. Changing File Name of Image
It is also important to change of the name of image. It effects in SEO.
Example: If you have a image of Ferrari Car. Then image name should be like - "ferrari-car.jpg"
3. Adding a Caption
After uploading images on website or blogger, you should always add a caption to the image, so that browser searches what exactly you are looking for.
4. File Size of Image
The size of image should be less. If you upload a image of 2 MB size. It will take a time to load a website. Thus the bounce rate of website will be more. So always upload the image of less size.