When is a white goose a Ross's Goose?

These two birds were observed and photographed by Lois Miller and Knute Andersson at Langlois, Oregon. Their posting started a typical OBOL-ian flurry of "Here's why I think it is..." posts, of which I was just as guilty as anyone.

After a ridiculous amount of time using ImageJ software to play with this photo, and Ross's Goose and Snow Goose images from Google Image searches, I believe the birds to be to be Ross's Geese, but leave the slight possibility that they are Ross's-Snow hybrids (as shown on p. 33 of the Smithsonian Field Guide to Birds.)  My graph in THIS SLIDESHOW may or may not be super-crisp science,  but it shows I have tried.  It has been pointed out that the last slide is of a Ross's compared to a GREATER Snow Goose....severe chagrin on my part!
Oh well ... it was fun...