medfilt3

3-D median filtering

Syntax

B = medfilt3(A)

B = medfilt3(A,[m n p])

B = medfilt3(___,padopt)

Description

B = medfilt3(A) filters the 3-D image A with a 3-by-3-by-3 filter. By default, medfilt3 pads the image by replicating the values in a mirrored way at the borders.

B = medfilt3(A,[m n p]) performs median filtering of the 3-D image A in three dimensions. Each output voxel in B contains the median value in the m-by-n-by-p neighborhood around the corresponding voxel in A.

B = medfilt3(___,padopt) controls how medfilt3 pads the array boundaries.

Examples

Use Median Filtering to Remove Outliers in 3-D Data

Create a noisy 3-D surface.

[x,y,z,V] = flow(50);
noisyV = V + 0.1*double(rand(size(V))>0.95) - 0.1*double(rand(size(V))<0.05);

Apply median filtering.

filteredV = medfilt3(noisyV);

Display the noisy and filtered surfaces together.

subplot(1,2,1)
hpatch1 = patch(isosurface(x,y,z,noisyV,0));
isonormals(x,y,z,noisyV,hpatch1)
set(hpatch1,'FaceColor','red','EdgeColor','none')
daspect([1,4,4])
view([-65,20]) 
axis tight off
camlight left
lighting phong

subplot(1,2,2)
hpatch2 = patch(isosurface(x,y,z,filteredV,0));
isonormals(x,y,z,filteredV,hpatch2)
set(hpatch2,'FaceColor','red','EdgeColor','none')
daspect([1,4,4])
view([-65,20])
axis tight off
camlight left 
lighting phong

Input Arguments

A — Input image

3-D, real, nonsparse, numeric or logical array

Input image, specified as a 3-D, real, nonsparse, numeric, or logical array. If the input image is an integer class, all the output values are also integers.

Data Types: single | double | int8 | int16 | int32 | int64 | uint8 | uint16 | uint32 | uint64 | logical

[m n p] — Neighborhood size

3-by-3-by-3 (default) | three-element numeric vector

Neighborhood size, specified as a three-element numeric vector, [m n p], of real positive integers. The values of m, n, and p must be odd integers.

Data Types: single | double | int8 | int16 | int32 | uint8 | uint16 | uint32

padopt — Padding option

'symmetric' (default) | 'zeros' | 'replicate'

Padding option, specified as one of the following values:

Value	Description
'symmetric'	Pad array with mirror reflections of itself
'replicate'	Pad array by repeating border elements
'zeros'	Pad array with 0s

Data Types: char | string

Output Arguments

B — Output image

3-D array

Output image, returned as a 3-D array of the same class and size as the input image A.