Copying and editing pictures on home computers has become common practice because of the user-friendly computers and printers available. Editing pictures taken by a commercial photographer can cross the line into copyright infringement and violation of copyright law.
Editing
Only the copyright owner has the legal right to change a copyrighted image or picture. If you change an original picture or create a new version of it and call it your work, you will have violated copyright law. You must get permission from the owner to change an original picture or piece of work.
Ownership
The photographer who takes a picture is the copyright owner. Once the picture is taken, it is considered copyrighted even if it is still in the camera and has not been printed. Copyright law protects works such as pictures even if they have not been registered with the U.S. Copyright Office.
Transfer of Ownership
The photographer can transfer copyright ownership to someone else if he does so in writing. You can research the copyright to locate the owner and if successful, ask for permission to make edits to the picture.