This is effect is pretty simple, you can also make collage effect. It is not any new or advance feature of photo shop it’s just a trick with combination of rectangle and selection tool follow the steps
- Insert an image
- Add a new layer
- Make some rectangle with rectangle tool as you can see in downside example image.
- Copy original image with cntrl +A and Cntrl +C
- Now click with control on layer one rectangle area
- All shape will be select then choose paste into from edit menu
- For make shadow effect double click on layer 1 and select drop shadow