Thanks both, appreciate your help.
After further research I discovered that I apparently first need to use
Selections > Load/Save Selection > Load Selection From Alpha Channel. That gives me this:
I'm not sure why that's necessary, because without that step I wouldn't see anything useful to help me work with the file. Promoting the original 'Background' to a layer and then placing a solid colour layer below it made no difference. Nor am I clear what I would typically do next after loading that 'selection'. It seems a lot more intuitive to use PNG files with alpha channel transparency, so you can then see the various areas of opacity.
The context is that these TGA files are inbuilt resources used by my video editor, Magix Movie Edit Pro 2014. I'm experimenting with them to better understand how they create their respective effects.
I've uploaded two more:
https://dl.dropboxusercontent.com/u/401 ... lloon3.tga
https://dl.dropboxusercontent.com/u/401 ... culars.tga
On inspection I assume this first one gets its transparency from the pure white background, while the balloons are 254,254,254.
The second looks all black on first opening and like this after the load operation:
--
Terry, East Grinstead, UK
