How to resize an image into size 256*256

I used the following code

J = J(1:256,1:256,:)

[r c]=size(J);

display(r); display(c);

But the value of c is displayed as 768.But the resized size is 256.What would be the error.And I cant use the command imresize since I need the third coordinate also.

Answer 1

[Image Analyst]

Never use size like that for a color image. Use

[rows, columns, numberOfColorChannels] = size(J);

For more info, see Steve's blog: http://blogs.mathworks.com/steve/2011/03/22/too-much-information-about-the-size-function/

Answer 2

[Thorsten]

Use

r = size(J, 1); c = size(J, 2);

If J is a color image, c returns the columns*3. See also my answer to your first question http://www.mathworks.com/matlabcentral/answers/218747-how-to-divide-an-image-into-blocks-and-find-the-rgb-values-of-each-pixels-in-a-block