how to make subplots with different heights?

I would like to plots below each other, but the first one is a picture with small height. I dont want large empty space. How to set the height of the first

subplot? Or automatically adjust it?
subplot(2,1,1)
imagesc(mypicture)
subplot(2,1,2)
plot(randn(100,1))

Answer 1

[Image Analyst]

Set the 'OuterPosition' property of the axes control that subplot creates

h1 = subplot(2,1,1);
set(h1, 'OuterPosition', [0,0.51, 1, .4]);
mypicture = imread('cameraman.tif');
imagesc(mypicture)

h2 = subplot(2,1,2);
set(h2, 'OuterPosition', [0,0, 1, .4]);
plot(randn(100,1))

Take great care with the position values because if the second axes overlaps the first one at all, none of the first one will show up.