Note: this is a work in progress. Many improvements are needed. For better specular maps generation, please use Laigter. Its also free and opens source.
Note 2: for better preview, you should also add normal map. You can generate it with Laigter, or with the Normal Map Dock for Godot
If you know how to use godot, any help is welcome! (Help is needed specially in GUI). The plugin is free and open source, but you can also support this (and other of my projects) by buying the pluging here.
This plugin creates a dock that lets you open a texture and create a specular map for it adjusting a few controls. The specular map is exported in the same directory than the original texture, with a "*_s.png" prefix.
