This part is really important to distinguish different material properties. I often simply select large chunks of the image which I copy and paste back onto an empty layer. I then flip/distort the image to get the overall reflection, and then proceed to mask it into the needed areas. For the window in the cg home, I ended up grabbing an image with enough foliage to emulate a tree line. I then screen this back on at a low opacity. For the bridge, I also used a Motion Blur filter before reflecting it back onto the surface.