[woofie]

I think yours is the only possible explanation other than photo shop ....but my gut tells me this is the bench or the same type of bench and the wall....
If it is the same type of bench the bench in the Obama pic is distorted and if it is the same wall just a different location .I think the pattern on the vertical joints will be consistent and unlike that in the Obama pic

[Tex-Con-Man]

If the contention is that a photo of the Grandparents was photoshopped to add Barack, the walls to the left of Grandpa and to the right of Grandma are irrelevant. The only editing necessary would be in the middle of the image, in the area around where Obama is sitting. The bench, the wall/sidewalk between his legs and the areas around his head and neck.

I see no evidence that happened.