imgaussfilt

2-D Gaussian filtering of images

Syntax

B = imgaussfilt(A)

B = imgaussfilt(A,sigma)

B = imgaussfilt(___,Name,Value)

Description

B = imgaussfilt(A) filters image A with a 2-D Gaussian smoothing kernel with standard deviation of 0.5, and returns the filtered image in B.

B = imgaussfilt(A,sigma) filters image A with a 2-D Gaussian smoothing kernel with standard deviation specified by sigma.

B = imgaussfilt(___,Name,Value) uses name-value pair arguments to control aspects of the filtering.

Examples

Smooth Image with Gaussian Filter

Read image to be filtered.

I = imread('cameraman.tif');

Filter the image with a Gaussian filter with standard deviation of 2.

Iblur = imgaussfilt(I,2);

Display the original and filtered image in a montage.

montage({I,Iblur})
title('Original Image (Left) Vs. Gaussian Filtered Image (Right)')

Input Arguments

A — Image to be filtered

numeric array

Image to be filtered, specified as a numeric array of any dimension.

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

sigma — Standard deviation of the Gaussian distribution

0.5 (default) | positive number | 2-element vector of positive numbers

Standard deviation of the Gaussian distribution, specified as a positive number or a 2-element vector of positive numbers. If you specify a scalar, then imgaussfilt uses a square Gaussian kernel.

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

Name-Value Pair Arguments

Specify optional comma-separated pairs of Name,Value arguments. Name is the argument name and Value is the corresponding value. Name must appear inside quotes. You can specify several name and value pair arguments in any order as Name1,Value1,...,NameN,ValueN.

Example: B = imgaussfilt(A,'FilterSize',3);

'FilterSize' — Size of the Gaussian filter

positive, odd integer | 2-element vector of positive, odd integers

Size of the Gaussian filter, specified as a scalar or 2-element vector of positive, odd integers. If you specify a scalar, then imgaussfilt uses a square filter. The default filter size is 2*ceil(2*sigma)+1.

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

'Padding' — Image padding

'replicate' (default) | numeric scalar | 'circular' | 'symmetric'

Image padding, specified as one of the following.

Value	Description
numeric scalar	Pad image with elements of constant value.
'circular'	Pad with circular repetition of elements within the dimension.
'replicate'	Pad by repeating border elements of array.
'symmetric'	Pad image with mirror reflections of itself.

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

'FilterDomain' — Domain in which to perform filtering

'auto' (default) | 'spatial' | 'frequency'

Domain in which to perform filtering, specified as one of the following values:

Value	Description
'auto'	Perform convolution in the spatial or frequency domain, based on internal heuristics.
'frequency'	Perform convolution in the frequency domain.
'spatial'	Perform convolution in the spatial domain.

Data Types: char | string

Output Arguments

B — Filtered image

numeric array

Filtered image, returned as a numeric array of the same class and size as the input image, A.

Tips

• If image A contains Infs or NaNs, then the behavior of imgaussfilt for frequency domain filtering is undefined. This can happen if you set the 'FilterDomain' parameter to 'frequency' or if you set it to 'auto' and imgaussfilt uses frequency domain filtering. To restrict the propagation of Infs and NaNs in the output in a manner similar to imfilter, consider setting the 'FilterDomain' parameter to 'spatial'.

• If you set the 'FilterDomain' parameter to 'auto', then imgaussfilt uses an internal heuristic to determine whether spatial or frequency domain filtering is faster. This heuristic is machine dependent and may vary for different configurations. For optimal performance, try both options, 'spatial' and 'frequency', to determine the best filtering domain for your image and kernel size.

• If you do not specify the 'Padding' parameter, then imgaussfilt uses 'replicate' padding by default, which is different from the default used by imfilter.

Extended Capabilities

C/C++ Code Generation

Generate C and C++ code using MATLAB® Coder™.

Usage notes and limitations:

• imgaussfilt does not support the FilterDomain parameter for code generation. Filtering is always done in the 'spatial' domain in generated code.

• If you choose the generic MATLAB Host Computer target platform, generated code uses a precompiled, platform-specific shared library. For more information, see Code Generation for Image Processing.

• When generating code, all character vector input arguments must be compile-time constants.

GPU Code Generation

Generate CUDA® code for NVIDIA® GPUs using GPU Coder™.

Usage notes and limitations:

• imgaussfilt does not support the FilterDomain parameter for code generation. Filtering is always done in the 'spatial' domain in generated code.

• When generating code, all character vector input arguments must be compile-time constants.

GPU Arrays

Accelerate code by running on a graphics processing unit (GPU) using Parallel Computing Toolbox™.

This function fully supports GPU arrays. For more information, see Image Processing on a GPU.