Blur

Blur[image]

gives a blurred version of image.

Blur[image,r]

gives a version of image blurred over pixel radius r.

Details

  • Blur is a filter function typically used for blurring an image. It is commonly used to suppress noise or to defocus an image.
  • Blur[image] is equivalent to Blur[image,2].
  • Blur works with 2D and 3D images. For multichannel images, it operates separately on each channel.
  • Blur[image,{r1,r2}] uses radius r1 in height and r2 in width.
  • Blur[image,{r1,r2,r3}] uses radius r1 in height, r2 in depth and r3 in width.
  • Blur[image] gives an image with the same underlying data type as image, except for "Bit" images. »

Background & Context

  • Blur is a filter function typically used for blurring (or smoothing) of an image. It can be used to suppress noise and local pixel variation or as an effect to de-focus an image.
  • Finer control over the amount and shape of blurring to be applied can be obtained using other filter functions such as GaussianFilter and ImageConvolve.
  • The converse of blurring is known as sharpening, which can be performed by functions such as Sharpen and ImageDeconvolve.

Examples

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Basic Examples  (2)

Blur a photo:

Specify the amount of blurring:

Scope  (5)

Data  (2)

Blur a binary image:

Blur a 3D volume:

Parameters  (3)

Vary the pixel radius to achieve different degrees of blurring:

Blur in the horizontal direction only:

Blur vertically:

Blur a 3D image in the vertical direction only:

Blur the horizontal planes only:

Applications  (7)

Reduce noise in a color image:

Remove Moiré patterns and high spatial frequencies:

Background equilibration:

Subtract the blurred background:

Sharpen an image using Blur:

Create soft shadows:

Find and anonymize faces in an image:

Create a mask that covers each face by a disk:

Emphasize faces in an image by blurring the background:

Display a motion pattern by blurring an animation in the temporal dimension:

Convert the animation frames into an Image3D object and blur along the slices:

Properties & Relations  (2)

Blur is equivalent to GaussianFilter with radius r, width σ=r/2, and "Fixed" padding:

Blur preserves the ImageType, except for "Bit" images:

Neat Examples  (1)

Blur an image outside an artificial focal plane, as in digital tilt-shift photography:

Find the in-focus area:

Introduced in 2008
 (7.0)
 |
Updated in 2012
 (9.0)