Selection with Pen Tool

Open photo.

Click to enlarge

Now double click the background layer. Name it as "front". Now make new layer. You can do this in several ways, I suggest Ctrl + Shift + N, name it as back and fill it with white. Or you can click on Create New Layer in Layers palette and put new layer behind "front" layer (while back layer is selected you can press Ctrl + Shift + [ ).

Now pick Pen tool (P) and start drawing around object you want to isolate. You zoom in and try to draw lines as near as possible to the object. Make sure that you work on "front" layer.

When you finish drawing this path go to the layers palette and click on Path. You'll see this picture

This means that you have working Path and now we can transform it to the selection. Simply slick on the button in the bottom

and this will transform path into selection. Now we only need to invert selection (Select - Inverse), make sure that the white is our background color and hit Del button. Now you have two layers, "back" layer which is all white and "front" layer which only have contour of the printer.

Click to enlarge

You can try this technique with bigger pictures after you try this example.