This technique can be used for Scattering some parts of picture. Very short technique.

1. Create a new file of any size, I’m taking 560x650px size with 72 resolution and RGB color mode.

2. Place any picture of your desire in it:


3. Select background layer and From the layer panel click on Add Layer Mask add-layer-mask button and select Levels:


Hit Ok you will get a new layer mask like:


4. Move mouse pointer in between Picture and Mask layer and click there, it will Mask the picture into Masked layer like:


5. Select Masked layer (Levels 1) and run the command Edit >> Fill, chose Black from Use list and hit OK


6. Pick Brush tool brush-tool and chose Square Brush from its type and Select 24 px brush Now press F5 key (or Window >> Brushes command), chose Scattering and give the following settings:


7. Click on the bottom right part of the picture like shown below:


8. Run the command Layer >> Layer Styles >> Drop Shadow and give the following settings:


Here is the final result.