I don't think that picture has been photoshopped. I just looked through the other released photos on the WFTV website, and most are just as bright as the one with the book. The sun was shining, plus I'm sure the camera probably flashed in the shade where the book was found.
Here is a photo from the same series of pics, and it's just as bright.
It makes me wonder if the book was possibly lying there closed, and someone opened it with the toe of their shoe or something. That could be why the inside pages are so bright - they had not been exposed to the sun.
Another pic of the crime scene on the same day.
Book pic