If I make the black background transparent the white (aircraft instrument) symbols are blurred. Why?
I know, I could my new background 50% transparent and place it in front but the result is not that good.
Possible to only let white color be in front or something alike? I cannot change the white only my new background. (dll)

You haven’t given us nearly enough information to be able to answer this.

What do you mean when you say that the background is “transparent?” The background can’t be transparent; the math just doesn’t work that way. Things are transparent relative to an opaque background. The background color should be a solid color. Furthermore, how did you make it transparent? What did you do that would cause it to be transparent? Transparent relative to what? What color values are you writing/clearing to, and what blend mode are you using?

Next, how are you rendering the “aircraft instruments”? What blend mode are you using for that?

I do a x-plane plugin so I don’t know what was used but I normally use:
/// Tell Xplane what we are doing
XPLMSetGraphicsState(0/Fog/, 1/TexUnits/, 0/Lighting/, 0/AlphaTesting/, 1/AlphaBlending/, 1/DepthTesting/, 1/DepthWriting/);


now I do drawMesh() and set it to 50% alpha value.
This I set before the instrument ok but colours don’t look very good.
Instead of making it 50% transparent I only want the white instrument symbols to be seen.
Placing it behind and removing the black instrument background makes the white symbols blurred. WHY???
Hence I’m looking around for a solution to only see white from below my new background.
Many thanks