The
Blur filters soften a selection or an entire image, and are useful
for retouching. They smooth transitions by averaging the pixels
next to the hard edges of defined lines and shaded areas in an image.

Before (left) and after (right) using the Lens Blur filter;
the background is blurred but foreground stays sharp
Note: To apply a Blur filter to the edges of a layer,
deselect the Lock Transparent Pixel option in the Layers palette.
- Average
-
Finds
the average color of an image or selection, and then fills the image
or selection with the color to create a smooth look. For example,
if you select an area of grass, the filter changes the area into
a homogeneous patch of green.
- Blur and Blur More
-
Eliminate
noise where significant color transitions occur in an image. Blur
filters smooth transitions by averaging the pixels next to the hard edges
of defined lines and shaded areas. The effect of the Blur More filter
is three or four times stronger than that of the Blur filter.
- Box Blur
-
Blurs an
image based on the average color value of neighboring pixels. This
filter is useful for creating special effects. You can adjust the
size of the area used to calculate the average value for a given
pixel; a larger radius results in greater blurring.
- Gaussian Blur
-
Quickly
blurs a selection by an adjustable amount. Gaussian refers
to the bell-shaped curve that is generated when Photoshop applies
a weighted average to the pixels. The Gaussian Blur filter adds
low-frequency detail and can produce a hazy effect.
- Lens Blur
-
Adds blur to an image to give the effect
of a narrower depth of field so that some objects in the image stay
in focus and others areas are blurred. See Add lens blur.
- Motion Blur
-
Blurs
in the specified direction (from –360º to +360º) and at a specified
intensity (from 1 to 999). The filter’s effect is analogous to taking
a picture of a moving object with a fixed exposure time.
- Radial Blur
-
Simulates
the blur of a zooming or rotating camera to produce a soft blur.
Choose Spin to blur along concentric circular lines, and then specify
a degree of rotation. Choose Zoom to blur along radial lines, as
if zooming into or out of the image, and specify a value from 1
to 100. Blur quality ranges from Draft (for fast but grainy results)
or Good and Best for smoother results, which are indistinguishable
from each other except on a large selection. Specify the origin
of the blur by dragging the pattern in the Blur Center box.
- Shape Blur
-
Uses
the specified kernel to create the blur. Choose a kernel from the
list of custom shape presets, and use the radius slider to adjust
its size. You can load different shape libraries by clicking the
triangle and choosing from the list. Radius determines the size
of the kernel; the larger the kernel, the greater the blur.
- Smart Blur
-
Blurs an
image with precision. You can specify a radius, a threshold, and
a blur quality. The Radius value determines the size of the area
searched for dissimilar pixels. The Threshold value determines how
dissimilar the pixels must be before they are affected. You also
can set a mode for the entire selection (Normal) or for the edges
of color transitions (Edge Only and Overlay). Where significant
contrast occurs, Edge Only applies black-and-white edges, and Overlay
Edge applies white.
- Surface Blur
-
Blurs
an image while preserving edges. This filter is useful for creating
special effects and for removing noise or graininess. The Radius
option specifies the size of the area sampled for the blur. The
Threshold option controls how much the tonal values of neighboring
pixels must diverge from the center pixel value before being part
of the blur. Pixels with tonal value differences less than the Threshold
value are excluded from the blur.