Attachment 88045

This is a question for all the brilliant repainters in our group - I realise I may be out of luck as far as a simple explanation goes, but anyway....

The image on the left is a _NORM.PNG.DDS from one of the Aeroplane Heaven Chipmunk liveries. The image on the right is a _NORM.PNG from their plain white texture 'repaint kit'. The _NORM.PNG looks like an old-fashioned bump map and seems to produce a different apperarance & reflection in the Sim compared with the _NORM.PNG.DDS textures; it's very obvious if, say, I swap out just one wing. Saving the PNG as a PNG.DDS makes no difference.

Is there a trick to saving these _NORM.PNG textures so they look and behave like the _NORM.PNG.DDS on the left? I'm still using paint.net, which opens the image on the left looking more like the one on the right. I may be hopelessly confused in trying to work 'old school' but I'd be grateful for any pointers.