I did this composite a few years ago as part of my 'puppy humor' series. I photographed the puppy in the bag against a black background in a studio. I then composited a photo of my wife with a store front in Salzburg, Austria, added subtle shadows beneath her shoes with the burn tool in Photoshop on 20% opacity, and then pasted into the scene the puppy in the bag. I call this picture 'shopping for puppies'. The reason the white hair of the Maltese puppy has such good detail is because the original background was black, and that kind of maximum contrast allowed me to use the blend mode 'lighten' which dropped out the black color completely when the puppy was pasted into the scene.