STE P BY STE P / Extra balls
1 Bring them together
If you only have a few balls, take several shots of them bouncing. Open Photoshop and go to File>Script>Load Files into Stack. Select all your shots and click on Open. Hit OK and the Layers palette should populate with all the images on separate layers.
To mask in the balls you want in the final image, select the top layer and hit the layer mask button at the bottom of the Layers palette. Paint over the ball in question to remove it. With your layer mask selected hit Cmd/Ctrl + I to invert the mask. Do this for all layers except one.
3 Save your work
Once you’re happy with your shot go to File>Save as and choose to save it as a PSD so you have a multilayer document to edit later. If you want to save it as a flattened image as well, go to File>Save as and change the dropdown to Save as JPEG.