Any photoshop experts know how to do this?

[growyourwings]

Speaking of Tumblr.  I found this image on Tumblr today.



I'm not asking about the photo composite aspect of this.  But rather the "vellum" looking finish on the whole thing.  Especially discernable on John's journal.    I don't think my eyes are deceiving me.  They might be as they are getting old and persnickety.   I did a quick Google but wasn't able to find something quickly.   

Anyone who loves to play in Photoshop - any ideas?  Perhaps a fog filter tinted a bit?   I haven't tried to play around yet.   This image keeps grabbing me every time I see it.

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