Nice, I followed the instructions and quickly made an icons mod. If anyone else plays at 4k and find the strategic icons too small to see, you may search the mod vault for "Larger strategic icons for 4k"
===========Icon editing tips============
For dds editing, I used a free Photoshop plugin called "Intel Texture Works"
After installing the plugin, you can open dds files in Photoshop. There will be a file opening prompt, on which you should choose:
"Load transparency as alpha channel" checked
"Load mipmap..." unchecked
When finished editing the file, there will also be a file saving prompt, you can set it like this:
Texture type: Color + Alpha
Compression: BC3 8bpp (Linear)
[leave other fields blank]
For batch processing using Photoshop actions, you should include the steps of file open and save in your recorded action, so the above settings could be remembered. Then in the batch setup window, check "Override Action 'Open' Commands" and set "Destination: None" (since you already recorded a save command).
I haven't tried GIMP plugins, but they should work similarly.