Starting again from scratch I created a Java application to display the generated heightmaps in a visual format. The first of which just populated the heightmap with a random value.
The next step was to implement the Simplex Noise algorithm. Looking good.
The black and white display was good but, I decided to tweak some of the display settings in my code in order to emphasise the noise pattern visually. Indeed this is just a set of rules on the rendering process the heightmap data remains the same as above. With the exception of a slightly larger value in artefact size.