Unfortunately... that's not how bumpmaps work. What they do is use specific colours to encode the direction of normals ( which the 3d engine converts into a type of shading that makes the surface look bumpy ), which means you do actually need the specific colours provided by the Nvidia converter plugins. They take an image with height data encoded as the brightness of a pixel as a source, so if you want a flat raised panel, it is just a strip of lighter colour, no shading.
Anyway to demo I attempted to convert the F9 bumpmap - which is less than ideal because it has shading, but it's just a rough example. Top to bottom:
* Source
* Converted to input for the plugin, not ideal
* Output of the Nvidia bumpmap plugin.
f9a-01-bump.jpg
Ideally in the source to the bumpmap generator the base colour would be 50% grey, the panel seams on the E9 would be say, 75% grey, and the rivets little white dots.
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