"One of a kind," Brown said on the way out of Singleton's funeral in L.A. on Monday ... "Loved his people. No negatives."

We couldn't find any evidence that Brown and Singleton ever worked on a project together -- seems the Hall of Famer just admired him for everything he accomplished.

In fact, when we brought up Singleton's resume -- and his most famous film "Boyz n the Hood" -- Brown talked about the impact he had on America.

"That was a tremendous breakthrough and one of a kind," Brown said.

You can tell from the clip, Brown appreciated everything Singleton accomplished and stood for.