I am working with very old model files that have BMP textures. The designers did not use a transparency in the textures or a separate alpha b/w texture. They used a specific color value that was then removed by the engine to create a transparency, similar to a chroma key. In this case, all textures used a bright purple/pink color.
I cannot modifying the original texture images by converting them to PNG and add an alpha. I would like to figure out how to do it all in nodes.
The goal is to have this value keyed out and transparent. I have been messing around in the shader editor and cannot figure this out. I've also been looking around online and in this forum, but the only search terms I can think of are chroma-keying which only results in Compositing results, which I don't believe is what I'm looking for.
Here is an example of the texture (its very small) and it's context:
Any help or direction would be much appreciated!