how to resize an image as per the required dimension

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

[Sarah Wait Zaranek]

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

[m n] = size(I) ;

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

[x y] = size(J);

This works for me.

[ramya s]

thank you so much

Answer 1

[Walter Roberson]

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

Answer 2

[shyama p]

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') ;

[Devi Timilsina]

thank you so much.

[priyanka gulhane]

thank you

[fahmii fitrii]

thank you for the coding.

Answer 3

[dipa teraiya]

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?

Answer 4

[salman saleem]

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

[Walter Roberson]

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.