Making your photos pop from the background by creating an illusion of a decrease in depth of field is covered in this tutorial.
When a lens focuses on a subject at a distance, all subjects at that distance are sharply focused. Subjects that are not at the same distance are out of focus and theoretically are not sharp. The zone of acceptable sharpness is referred to as the depth of field.
Check out some of these Flickr pool photos that showcase some depth of field.
OK, lets put some ‘fake’ depth of field into an image that otherwise has a some what large depth of field. The image is fine, but if we make these adjustments the subject in the photo would pop and call that much more attention to itself as you can see with the final comparison above. The original image is on the left and the new depth of field added image is to the right.
Step 1. Open your photo and determine the subject to be isolated. Duplicate the layer and on the top layer silhouette the subject by using the Pen Tool.
Step 2. Tweak the selection with the Quick Mask Mode. You can fix all the little place you were off with your initial selection. Control/Click on the layer of the isolated subject and then select the Quick Mask Mode just below the Foreground/Background Color Swatches on the Tool Palette. Using the Paint Brush add to the selection by painting white and take away from the selection with black. Once the selection is tight, copy and paste the subject on its own layer.
Step 3. Add Gaussian Blur to the duplicate layer of the entire pic. This will leave in your Layer Palette a blurred copy of the entire picture and the unaltered version on the layer below it.
Step 4. Delete some of the blurred layer using a Feather Selection. We want to keep some of the original image to complete the illusion. Use a Square Marquee and select the bottom half or quarter of the image. Go to Select/Feather and input a number, experiment with the range. I used a Feather Selection of 35. Then hit Delete.
Step 5. Layer Mode options can be used to further enhance the image. Play with the various modes and see how they react with the underlying duplicate layer. These are some various modes that I thought could possibly be used- the differences can be subtle.
Final. Flatten the image and adjust the Levels and use some Selective Coloring to bring out the blacks, whites or any other color in the image.