Alternative Text (commonly referred to as alt text) is an informative description
of an image as it relates to the content
on the page.
There isn’t an exact science to writing alt text.
Image of, Photo of, Logo of, Profile of, etc
Assertive devices already say “graphic” or image before reading the alt text. Simple describe the image without identifying the image type.
Profile images can simple be the person’s name. A logo can simply be the company’s name.
Be sure that all users are getting the same information. Don’t provide some information to one type of user and not the other.
For example, this image of the toddler pulling on his ear provides additional information in the alt text.