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 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 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.