See the following link:

https://www.mathworks.com/matlabcentral/fileexchange/39559-automatic-terrain-generation/content/generate_brownian_mesh.m

Thanks Ahmed Tarawneh for your kind response. As already i have gone through this link but i am confusing the two input parameter like -n - Number of iterations

zm - Initial heights. Actually i need the surface image of size 256*256, for which what should be the appropriate choice for  Number of iterations and Initial heights

See attached a function for this algorithm.

You can run it with:

imagesc(MidPoint(8,0.5)),colormap('gray')

for a surface in size 257*257.

The image above is an example for a result.