How to import special image heightmap for a level?

I have an image linked below that was extracted from a umap file. When I import it as a heightmap for a level the outcome in the editor is all bumpy, unlike the original terrain. I think where there is purple is an incline (like a hill or mountain). If anyone could help that would be great.

Hi, basically a heightmap should be grayscale (not sure what happens if you try to import a colored one) and white means up, black means down. Next you would need to scale your landscape in ue4 in the z-axis (if you use a program like worldcreator 2 to generate the landscape it will show you the z-scale needed in unreal engine when you exporting the heightmap).