Static builds of LuaImg are available for Windows and Linux (Ubuntu). The latest (alpha) builds containing Windows XP (32 bit) and Ubuntu Precise LTS (AMD64) are linked below:
Lua is MIT licensed and (c) PUC-Rio. The extensions to the Lua VM and the LuaImg code are (c) David Cunningham and also released under the MIT license.
The source code for LuaImg lives in the Grit svn repository. Grit is much larger than Luaimg, as it is a full game engine with example content. If you want to avoid checking out the entire repository, get the luaimg and dependencies directories only. The compilation instructions for LuaImg are similar to the Grit Compilation Instructions page, but with some differences (unless you want to build all of Grit as well).
On windows, use the VC solution file and build the Luaimg project. That will build all the necessary dependencies.
On unix-based OS, the steps required are a subset of those for the Grit project. You do not need to build Bullet or Ogre (or Grit). You do still need to build ICU because of the text rendering support in Luaimg. You also need to build squish, which is used for DXT compression (for dds export), and gif_lib. Run make in their directories in dependencies/ You'll need libreadline installed (on Ubuntu: libreadline-dev). The actual Luaimg executable is built by running make in the luaimg dir.
If you have any trouble, contact us on the Grit IRC channel or forums, see the Grit website for details.