[ART] How to make heightmaps?

[TheVileMushroom]

I have been messing around with height maps in the material editor for a very long time now and I just can not figure out how they work.

Whenever I try to make a heightmap, no matter what texture I use (even totally black images), this is the result: Image1 It produces this strange warped effect around the top and bottom edges of the texture.

Now if I were to copy and paste a texture (in a image editor like photoshop) and save the copied texture to a new .tga file, the same warped effect would happen. But if I just used the normal .tga file default to Amnesia, it works perfectly fine!

I just don't understand how heightmaps work and I need help on how to properly create and export them. This is a height map I tried to create from photoshop with 32 bits/pixel with Compress (RLE): Image2