Image Release form

Query. I wrote a book for a friend about his life and in it celebrity photos - basically he poses with different celebrities. My question is, should I contact each and every celebrity and ask them to submit a Standard Release Form should they wish for the use of their images? We're going to put them in the book, but isn't it polite to inquire about an image relase?
Thanks

Well, normally artists have the right to their own image and they utilize an Intellectual Property firm to handle any transactions made from their image. If I have a photo of a celebrity who posed with me somewhere and I wanted to put it into a memoir book about my life, wouldn't that artist have a release form for me to sign if they agreed to have their photo in my book? Or, do I have to ask them for the release at all? Or, do I have to find a general release form myself and ask the artist to sign it? Hope I made myself clear here. If I didn’t do let me know. thanks