Is "Sunset Boulevard" the name of a photo agency?

We have a photo of James Dean that we’re running that has “SUNSET BOULEVARD/CORBIS SYGMA” as the credit. What does the “Sunset Boulevard” refer to?

Now, the photo isn’t from the movie SB. (Dean wasn’t even in that, AFAIK.) But a cursory search has turned up other celeb photos with “SUNSET BOULEVARD” as a co-credit.

Is this the name of some large photo agency/archive/collection? Because I’ll be damned if I can find anything about it.

Hopefull Eve will offer an answer.

She did that wonderful lament some time ago about Bill Gates(Corbis/Sygma) scooping up all the photos from years gone by and putting them underground with limited access for scholars.

Calling Eve…