Use the Image as a Frame
One smart effect is to create a photo frame using the image itself. With the image open, make a rectangular selection a little way inside its borders. To ensure that it’s nice and even in size and placement, start the shape in the middle of the image by clicking in the middle of the image and holding the Alt key (Option key on the Mac) as you draw the shape from the center out.
Invert the selection by choosing Select > Inverse, add a new layer, and fill in the selection with black. Invert the selection again and enlarge it by choosing Select > Modify > Expand and set the value to the thickness of a thin line (try four pixels on a small image and a larger value on a larger one). Invert the selection again and choose Layer > New >Layer Via Cut to cut the excess black color to a new layer.
Set this layer’s blend mode to Multiply and decrease its opacity so it darkens the image surroundings. Because the hairline is on a separate layer, you can add a shadow to it by adding a layer style or changing its color by Control + clicking (Command + clicking on the Mac) on the Layer thumbnail, selecting a new background color, and pressing Control + backspace (Command + backspace on the Mac) to replace the color (see Figure 5).
Figure 5 Use the image to create its own frame with this simple effect created by blending a layer into the image to darken it.