Matlab Image Resize

Introduction to Matlab Image Resize

MATLAB is designed to store most of the images in the form of two-dimensional matrices. In those matrices, each element corresponds to a distinct discrete pixel present in any stored image. The Image Processing Toolbox software available in MATLAB supports several operations that can be performed on images. The function of the resizing images is one of those functionalities. Resizing of any 2D image in MATLAB can be performed using imresize() function whereas imresize3() is used for resizing of 3-D volumetric intensity image.

Examples to Matlab Image Resize

There are different ways in which an image can be resized in a MATLAB program. They are:

1. Resizing using Magnification Value

The image can be magnified or shrink by a specific factor mention within the imresize() command.

Code:

Img = imread('MyIMage.png');% Reading input image from workspaceimshow(Img) %Showing given image on the output windowtitle('Original Image')Out = imresize(Img,0.5);imshow(Out)title(' Resized Image') axis off

Output:

2. Resizing usingfixed dimension Value

The image can be magnified or shrink to definite dimensions, mentioned within the imresize() command.

Code:

Img = imread('MyCircuit.png');imshow(Img)Out = imresize(Img,[100 150]);imshow(Out)axis off

Output:

3. Resizing using the specific interpolation method

The image can be magnified or shrink using a specific interpolation method, mentioned within the imresize() command.

Code #1

Img = imread('MyIMage.png');imshow(Img)Out = imresize(Img,0.5, 'nearest'); %Applying the interpolation method ‘nearest-   %neighbor’imshow(Out)axis off

Output:

By default, imresize() has an antialiasing feature turned on in order to limit the impact of aliasing for the output image for all interpolation types except for the method ‘nearest- neighbor’. The antialiasing can be turned off by specifying the ‘Antialiasing’ parameter having value as False.

Code #2

Img = imresize(I,.75,'Antialiasing’, false);figure, imshow(Img)

Output:

4. Resizing indexed images

An indexed image specified in the form of a numerical array can be magnified or shrink using a scaling factor, mentioned within the imresize() command.

Code:

[M, map] = imread('trees.png');
[O, newmap] = imresize(M, map, 0.5);
figure
imshow(X,map)
figure
imshow(Y,newmap)

Output:

5. Resizing RGB Image to the Specified Size of Output Image

An RGB image specified can be magnified or shrink to a definite dimention, mentioned within the imresize() command.

Code:

RGB = imread('trees.png');
RGBOut = imresize(RGB, [64 NaN]);
figure
imshow(RGB,map)
figure
imshow(RGBOut,newmap)

Output:

Input Arguments and Attributes

Below are the table explain arguments and attributes:

Additional Note

Below are the points explain additional information:

• The function imresize()has been introduced in version 5.4 (R2007a). In earlier versions of the Image Processing Toolbox™, a different algorithm is being used by default. If the same results are expected to be produced by the previous version programming, instead of the function imresize(), the function imresize_old() needs to be adapted.
• The operation of imresize() method is carried out either by CPU or GPU. There is a numerical difference between the results of imresize that occurs on the bottom and rightmost borders of the resultant image. But this can be barely noticed by the naked eyes.
• In case of the resultant image not having size with an integer value, the imresize() function does not use the specified scaling factor. Imresize() uses ceil while calculating the size of the output image.
• If the input image has more than two dimensions, then imresize() supports performing resizing operation only to the first two dimensions.

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This is a guide to Matlab Image Resize. Here we discuss an introduction to Matlab Image Resize, syntax with attributes, examples to resize images. You can also go through our other related articles to learn more –

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