Background extraction can be done using several techniques some more straightforward than others, magic wand, magic eraser, extraction filter and color range. When colors are very close to each other in the digital spectrum the procedure can become very labor intensive and it all boils down to how badly you want to extract an image from its background. In your image it becomes immediately apparent that the background is lighter than the foreground image you want to extract. An easy way of determining this if it isnt at first obvious, is to squint your eyes and see where the shadows and lights aggregate in the perceived image. If the image is too dark and the perceived image is one big mass of darkness (or the image may be too light) then you know youre in for a very long night of extraction (sometimes it takes days). The most labor intensive way and the most accurate is using the pen tool to carefully outline that part of the image you want to extract under zoom magnification. Using this approach you have the option of fine-tuning your selection since the individual vertices created by the pen tool can be moved and place precisely where you need them. This comes in very handy when correcting selection mistakes because you can even add or subtract vertices as you need them. Finely you can convert your pen tool path into a selection in the Path palette and then save your selection either to disk or to the channels palette. But heres another way of extracting an image from its background when the lights and the shadows are apparent. Make two layer copies of your image and hide the bottom most (your original). You now have the two copies to work with. Highlight the uppermost copy and from the Filter menu select Others->High Pass. Set the high pass filter to 4.8 radius pixels. Make this layer mode an overlay and merge down to the first layer copy of your image (Ctrl+E). Doing this will make your dark edges more distinct and contrasty. Now in the Image menu select Adjustments->Threshold and for this image you can leave it at the default 128 but you will note that sliding the up arrow under the histogram alters your whites and blacks selections. This will separate your lights from the shadows leaving the background in white and your foreground image in black. Looking at this layer in black and white we realize that this layer can now be used as an alpha channel to extract our foreground from our background. But in order to do this properly we need to reverse the image so that the foreground image becomes white and the background becomes black. Apply Ctrl+I and your layer colors reverse. Making sure that your threshold layer is the only layer selected click into the channels palette and grab the red channel and drag it down to the create new channel icon next to the trash can icon at the bottom of the panel. You now have an alpha channel that will select your foreground image. Holding the Ctrl key while clicking this alpha channel will automatically select the foreground image in your layers palette.