how to resize an image as per the required dimension

Question

ramya s 2011-3-16

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https://ww2.mathworks.cn/matlabcentral/answers/3326-how-to-resize-an-image-as-per-the-required-dimension

评论： Walter Roberson 2023-5-16

i am doing my final yr project on steganography. and my project s suit only for square matrix images. (i.e, 256*256 512*512 1024*1024) like that images. i need images for that. wen i tried to resize other images it does not works.

for eg., I=imread('post.jpg');
[m n] = size(I)
J = imresize(I, [256 256]);
[x y] = size(J)

the output i m getting is m = 324 n = 512

x = 256 y = 1156

i do not know why it is like this. i am not getting any errors. help me what to do what shall i do now? please help me its very urgent

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Sarah Wait Zaranek 2011-3-16

I =randi(324,512,'uint8');

[m n] = size(I) ;

J = imresize(I, [256 256]);

[x y] = size(J);

This works for me.

ramya s 2011-3-16

thank you so much

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Answer 1

Walter Roberson 2011-3-16

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Your image is 3 dimensional (RGB), not 2 dimensional.

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Answer 2

shyama p 2011-3-17

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编辑：Walter Roberson 2017-11-9

在 MATLAB Online 中打开

I1=imread('post.jpg');
I2 = imresize(I1,[256 256]); 
In=rgb2gray(I2); % use if the image containing RGB value 3
figure;imshow(In);
imwrite(In,'yi.jpg') ;

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priyanka gulhane 2017-11-7

thank you

fahmii fitrii 2019-9-11

thank you for the coding.

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Answer 3

dipa teraiya 2018-4-24

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hello friends i have image of dimension is 84 * 34 and size of image is 16.1 KB Now other image of dimension is same but size of image is different is 16.4 KB so pls tell me which code can be applied when increase the size of image?

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Answer 4

salman saleem 2020-10-12

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My question is how we can reduce the size of image by taking mean?

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Walter Roberson 2023-5-16

在 MATLAB Online 中打开

Suppose that you replace each N x N block of pixels with the mean value of the pixels in that block. Then your image with be 1/N times as large, but still similar.

For example:

img = imread('flamingos.jpg');

imgd = im2double(img);

img2x2 = (imgd(1:2:end,1:2:end,:) + imgd(1:2:end,2:2:end,:) + imgd(2:2:end,1:2:end,:) + imgd(2:2:end,2:2:end,:))./(2*2);

imshow(imgd); title('original');

imshow(img2x2); title('mean of 2x2 blocks')

whos img img2x2

Name Size Bytes Class Attributes img 972x1296x3 3779136 uint8 img2x2 486x648x3 7558272 double

You can see that the two images are visually very very similar, but the second image is only half the number of rows and columns of the first image.

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