Gaussian Blur Effect; Lens Blur Effect; To Use The Lens Blur Effect - Adobe AFTER EFFECTS 7.0 Manual

Original (left); with effect applied (right)

Gaussian Blur effect

The Gaussian Blur effect blurs and softens the image and can reduce the visibility of noise. Specify whether the blur
is horizontal, vertical, or both. The layer's quality setting does not affect Gaussian Blur.
This effect works with 8-bpc, 16-bpc, and 32-bpc color.
Original (left); with effect applied (right)

Lens Blur effect

The Lens Blur effect introduces the appearance of a narrower depth of field by blurring some objects in an image,
while leaving others in focus. Use a simple selection to determine which areas become blurred, or provide a separate
alpha channel depth map to specify exactly how you want the blur added; black areas in an alpha channel are treated
as though they're at the front of the photo, and white areas are treated as if they're far in the distance.
The way the blur appears depends on the size, number, rotation, and curvature of the blades of the iris.
This effect works with 8-bpc and 16-bpc color.
Original (left); Depth Map layer (center); result (right)

To use the Lens Blur effect

1 Select a layer, and choose Effect > Blur & Sharpen > Lens Blur.
Choose a source layer (if you have one) from the Depth Map Layer menu.
2
Set the Blur Focal Distance parameter to the depth at which the desired pixels are in focus.
3
If you want to invert the selection or alpha channel you're using as the depth map source, select Invert Depth Map.
4
Modify the iris with any of the following settings:
5
The polygon to use as the iris shape.
Iris Shape
The roundness of the edges of the iris.
Iris Blade Curvature
ADOBE AFTER EFFECTS 7.0 392
User Guide