M, N = I.shape

    for x in range(0, M):
        for y in range(0, N):
            if((I[x, y] * const) > 255):
                I[x, y] = 225
            elif((I[x, y] * const) < 0):
                I[x, y] = 0
            else:
                    I[x, y] = I[x, y] * const