Interesting on lots of levels!
I assume (since Mr. Kellogg was probably not there) that someone took the photo and later sent it in to Kellogg's studio to be made into a RPPC.
Puzzling though, as I've always assumed that a professional, traveling photographer took them - but I must be mistaken.
Perhaps sending away to have them made with your own photographs was always a possibility.
What do you think, Alan?
Also, although (I believe) I've only seen vintage men in long nightshirt-type sleepwear, I am quite surprised to see that Asian type neckline on his pajamas. It strikes me as a very traditional female decorative touch!
And finally, looking at the wall - it appears that a larger picture/mirror hung where the edge of the current picture can now be seen. There wasn't much of an attempt to cover up the non-faded wallpaper, was there? Or do you think that's just a sunlight/window reflection?

Also, I wonder if he's home for a visit - or staying at a hotel.
The things we don't know...

Thanks, Deborah, for all your observations and comments! I totally missed the outline of the larger picture on the wall! I'm not sure about the sleepwear -- I looked around a bit to make sure that men were wearing pajamas in the early twentieth century but couldn't find much about specific styles.

And I think you're correct in assuming that an amateur photographer took this photo, which was later developed and printed as a RPPC at the Kellogg Studios. As early as 1906, you could also send a roll of film to Kodak for printing on a postcard backing. "Unskilled amateurs became big buyers of commercially produced photo postcards as well as the products that allowed them to do their own handiwork," meaning that they could either send film away for processing into RPPCs or purchase the paper and supplies to do it themselves. This info comes from Robert Bogdan and Todd Weseloh's book, Real Photo Postcard Guide: The People's Photography (Syracuse University Press, 2006). See the section on "Amateur and Snapshot Photographers," pp. 89-91, in the book, which is full of great examples of all kinds of photo postcards.

Thanks for the info. Alan. As I was writing it I was thinking, "Of course they must have sent it away - how many traveling photographers do you think there were?" but it had just not struck me before - so now I'm feeling a little foolish!
Do you have that book? I'm thinking I might try to ILL it.

This certainly is an unusual photo to have from so long ago. As the man appears to be travelling, perhaps the pajamas came from a trip to an asian country - thus the asian style top to the pajamas. Looks like someone set the camera down for a long exposure (seeing the out of focus bit of foreground), but not so long that the man's smile is not blurred.

Fascinating!

So many nice details to this, Alan. I like the quilt especially.