this is partially preference. I prefer to be able to see Antiair and Point Defense at a glance. It is less of a concern which enemy they belong to, and more ( don't fly your asf's over the pink sams, they do have the player color as an outline ).
I have tried similar approaches that other mods do, with simple color outlines, but the issue that I find is that due to how the icons are compressed, the colors will look funny, or bleed into each other, OR they look great on one player color, but not another.
or they work great at larger size, but terrible at another size. It's a balancing act. I find that more pastel colors, such as lighter pink, and light tan for PD's do not look overpowering, but are prominent enough to show up. Some colors such as RED, i ran into issues using, or they don't contrast well when you have 16 player colors across the screen.
I don't have the best eye acuity, so having to zoom in just to see a tac, PD, antiair, etc was an issue for me.
For editing, consider using GIMP with dds plugin, or Photoshop. If you don't edit the channels/mask properly, you can wind up with artifacts that won't show up in the file, but will when the file is converted, depending on how you saved/edited/converted.
It took me too long to figure that out.
You would preferably want the uncompressed versions, and use a conversion program to go to bc3/dxt5 after the fact. If it's gray, that is placeholder of player color. If you want an actual gray color, there is a RGB value that can be used, but i forget it at the moment.
If anyone wants the uncompressed files in various sizes, i would be happy to provide them. This is a blanket permission to use any of my icons how you see fit, but provide credit where credit is due. The T4 icons are from IKIT, so those are credit to him, with a few exceptions of my own.