Using Dolphin, you can trigger "Dump textures" in the GFX options. In terms of rock9, this will construct the tile parts to be used on the screen into a texture. Thing is, it can only construct what it can 'see', based on emulator or system capability. But, the good part of this method is the coloring of the texture; I was able to see most of the mugshots on Stage Select, so if that helps in creating a palette based on true color values and the colors rendered by tiling programs...
In the attached zip are some Targa (.tga) files of some random things I was able to get. You'll need an imaging program like Paint.NET to open them. I also suggest installing a
thumbnail extension for Windows to support Targa.