I think Njen referred not to a bitmap loader-I\O plugin\map but to a separate and specifically optimized image format like some of the renderers out there have.
There are already some image formats which are better suited for 3d rendering (or at least better for some specific renderers and some specific scenarios) like uncompressed tiff or some lossless variants of jpeg2000 (which has sadly very limited support) and a couple of others, mainly due to their memory mapped nature, but I'm not exactly sure if Corona utilize that technology or not - Mental ray for example does -
http://download.autodesk.com/us/maya/2009help/mr/manual/node20.html or at least did when that was published. + there are some internally mip-mapped\eable image formats but again I'm not sure if Corona can or will utilize that as well as are there any real benefits to that (if any) and aren't there some downsides to those - remember the thing with romullus's "favorite" and rightfully dreaded bitmap proxies )
Again, I'm not totally sure of the benefits and downsides of using those memory mapped formats, though, from my experience, it seems what large, and I mean like REALLY Large res (in my case some terrain satellite imagery of 25000x25000 resolution weighting almost 3.5GBs) in an uncompressed tiff format, used with Corona, rendered a bit faster and 3ds max was generally more responsive with it than with the other compressed and non memory mapped format types I tried using for that same purpose, of course it came with increased memory (both ram and vram) usage during the modelling yet totally or almost the same usage during the rendering itself (which isn't surprising), and it seems that the rendering was starting faster. Still that needs some more thorough testing or even better some explanation\clarification from Corona's team, because I may be exaggerating the benefits and those may only be my wishful thinking or some other sort of placebo effect + that was around 2 or more years ago and I may have simply forgotten that scene's as well of that particular monster of a texture's exact behavior.
So my point would be, such - probably Corona does not need to have it's own image format but instead should be taught to utilize (if it does not already do so) those already present and relatively easily editable ones instead of inventing the wheel anew so to say ). Or maybe I just misunderstood the whole point of the discussion ))
And yeah - here's
http://forums.cgsociety.org/showthread.php?f=2&t=607414&page=1&pp=15 some quite old but interesting discussion around and on that particular theme, some of you might find interesting too - there are many speculations but some facts are present as well )