How to superimpose the motion vectors over an image?

my motion vector plot i obtained using the quiver function on matlab is not the same as the image. My image size is 420 by 560 and my motion vector plot is 30 by 30. How can I do the superimposing over the full range of the image. what I have so far is this : figure(1); imshow(img1) hold on quiver(MVx(end:-1:1,:), MVy(end:-1:1,:)); %MVx and MVy are the x and y component of the motion vector.

Plz help