Is there a convenient way to apply a lookup table to a large array in numpy?

I’ve got an image read into numpy with quite a few pixels in my resulting array.

I calculated a lookup table with 256 values. Now I want to do the following:

for i in image.rows:
    for j in image.cols:
        mapped_image[i,j] = lut[image[i,j]]

Yep, that’s basically what a lut does.
Only problem is: I want to do it efficient and calling that loop in python will have me waiting for some seconds for it to finish.

I know of numpy.vectorize(), it’s simply a convenience function that calls the same python code.