subtraction of two images

I have two images with different dimension. I need to perform subtraction on it. I am not able to do it and don't know how to fix the error. Can somebody tell me the right code in matlab? i am unable to post images here. each time i do it i get error saying matrix dimension must agree. how shall i solve it

R=imread('If.jpg');

S=imread('j.jpg');

f8=R-S;

below is the description of my image u= imread('If.jpg');

whos Name Size Bytes Class Attributes

u 363x484x3 527076 uint8

v= imread ('j.jpg');

whos Name Size Bytes Class Attributes

v 900x1200x3 3240000 uint8

i am unable to subtract it because of the error minus Integers can only be combined with integers of the same class, or scalar doubles.

Error in ==> file1>filter_Callback at 695 f8=If-J;

[snehal dahiphale]

use imresize and then perform subtraction

Answer 1

[David Sanchez]

You can not subtract images with different sizes the same way you can not subtract arrays with different lengths:

a=[1 2 3 4];
b=[1 2];
c=a-b; % -> !!!!! this will yield an error, dimensions must agree. Same for your images

Perform a crop of the biggest image with the dimensions of the smallest, use imcrop:

doc imcrop

and then subtract the smallest image and the crop from the biggest.

[vidya]

thank you for replyin sir...but when i perform crop of the big image i am getting error msg ssayin > minus Number of array dimensions must match for binary array op.

Error in ==> file1>filter_Callback at 703 f8=J-If; how shall i correct it