How to use Svd

If I want to SVD an image, I cant do this?

a= imread('C:\Users\Acer\Desktop\Inves\teddy.jpg'); 
s = svd(a)
[U,S,V] = svd(a)
[U,S,V] = svd(a,0)
[U,S,V] = svd(a,'econ')

[David Young]

Is the problem that the code doesn't work because the image is not a matrix, because it has 3 colour planes?

Can you say why you want to take the SVD of the image? What use do you expect it to be? What problem are you trying to solve? Is there some mathematical background to what you are trying to do?