About 3/4 of the way back, there's a fairly abrupt change in color, and the angle there looks a little off as well.
To me this dick doesn't look photoshopped. There's a twist, rather than a simple bend in the proximal penis, causing slight left and downwards angulation; the darker area is shadow due to this. The superficial dorsal vein and one of the more lateral superficial veins follow this twist. The slight bulge just in front of the balls is the corpus spongiosum also following this twist in the penis. This means that what you are seeing from the left is more of the top of the penis than you would normally expect. This makes it appear thicker as the corpora essentially form an inverted triangle when erect, with the larger, more solid corpora cavernosa together on the top.
With respect to length, if you imagine it pushed up against his belly, it doesn't quite reach his belly button, which is entirely in keeping with a larger than average - but not massive - penis (prob smaller than many on here), with no need for digital jiggerypokery to achieve this. Plus, a friendly camera angle has been used.
That doesn't take away from it being a good-looking picture.
The defence rests, your honour.