How to use image sc and contour?

Let's say I have a random 2000 by 2000 matrix. Numbers range from 1 to 1000

I want to be able to use imagesc(matrix) then with a yellow contour if the number is between 500 to 550. How to do it?

Answer 1

[ChristianW]

n = 20; % 2000 takes long calculation time fot contour
X = randi(1000,n);
[C,h] = contour(X,[400 600]); axis image
set(h,'ShowText','on','LineWidth',2)
colormap([1 0.6 0; 1 0 0]) % own colormap, orange and red