I know and follow many of the scientists and astrophotographers whose work is featured on APOD, many of them aren't professionals but they dedicate their time and images because of their love of the Cosmos - and it is a true labor of love.
This is from the About page of APOD:
Astronomy Picture of the Day (APOD) is originated, written, coordinated, and edited since 1995 by Robert Nemiroff and Jerry Bonnell. The APOD archive contains the largest collection of annotated astronomical images on the internet.
..
In real life, Bob and Jerry are two professional astronomers who spend most of their time researching the universe. Bob is a professor at Michigan Technological University in Houghton, Michigan, USA, while Jerry is a scientist at NASA's Goddard Space Flight Center in Greenbelt, Maryland USA. They are two married, mild and lazy guys who might appear relatively normal to an unsuspecting guest. Together, they have found new and unusual ways of annoying people such as staging astronomical debates. Most people are surprised to learn that they have developed the perfect random number generator.
About image permissions:
All the images on the APOD page are credited to the owner or institution where they originated. Some of the images are copyrighted and to use these pictures publicly or commercially one must write to the owners for permission. For the copyrighted images, the copyright owner is identified in the APOD credit line (please see the caption under the image), along with a hyperlink to the owner's location. NASA images are in the public domain, official guidelines for their use can be found here. For images credited to other owners/institutions, please contact them directly for copyright and permissions questions.