Yves,
thank you for your efforts.
find a tga dumper who can be of great help (enum...)
The TGA header contains 18 bytes in which all information about the image and its display is stored. Reading these out and interpreting them correctly is really not witchcraft.
What MS has written in code for this simple task is very cumbersome. On the PowerBASIC page, you can find a TGA Viewer, written by me with PB 3.5 (DOS compiler).
The program can display True Color images and TGA images with DAC (256 colors) correctly. To be able to display large images, I used the XMS memory and worked with
VESA bank switching. The credits of the program still show my old mail address at CompuServe. So the program was written in the mid 90s.
Of course, my program has weaknesses. I am in the process of changing that. At that time VESA 2.0 was up to date and my program hard coded e.g. some VESA modes.
The right thing to do, of course, is to get the list of available VESA modes and scan them etc.
Gunther