Limited RGB = 16-235 RGB, Video Levels'.
Full RGB = 0-255 RGB, PC Levels'.
Games and the XMB are rendered in RGB. I believe it is natively in the 0-255 PC range. (which you would expect, as it is an nVidia graphics card in there) People have also reported seeing additional posterisation when sending Video Levels as there are less steps of gradation available.
The levels are remapped automatically whether you are in Full or Limited RGB. By that, I mean that whether it is in limited or full RGB, you will always see information below/above 16/235 in the photo viewer etc.
BD/DVD is natively YCC, 16-235. If you set BD/DVD output to YCC rather than RGB or Auto, the Full/Limited RGB setting will have no effect whatsoever.
Super White enables/disables the display of BTB/WTW information with BD/DVD playback in YCC. If you play back BD/DVD in RGB, the PS3 will always clip it.
Many displays do not support Full RGB, or do not work with it correctly when in Auto mode. With some displays (Pioneers for example) forcing them into PC levels will stop them auto-switching into YCC for BD/DVD meaning that you have to either use RGB for everything (prioritising game image quality) or use limited RGB for games and YCC for BD/DVD. (prioritising BD/DVD IQ)
To test whether your display supports Full RGB or properly switches into it automatically, first set the system to Limited RGB.
Now either download this onto your PS3 via the browser, or load it from a memory stick: http://sr-388.net/images/patterns/Brightness.jpg
Adjust the brightness control on your display notch-by-notch until the 1 is just
visible a notch lower and it would disappear.
Now, switch your PS3 into Full RGB mode. Is 1,2,3,4 still visible or are you now looking at a black screen?
If 1,2,3,4 is visible, your display properly supports auto-switching into PC levels. If not, see if you have an option in the menus to switch between PC/Video levels. (often labelled something like black level high/low') Switching to PC levels should restore the 1,2,3,4 on your display.
The 1 or possibly even 2 may disappear so you might need to adjust brightness a couple of notches to get it to display properly again.
If it all disappears and you have to make significant changes to brightness (e.g. 10, 15, 20 notches, assuming a scale of 1-100) then it is not
If you can't see 1,2,3,4 at all after switching the PS3 into Full RGB and don't have a black level option on your screen, it does not support it and you should set it back to Limited RGB.
Personally, I feel that it is a bit of a misnomer calling it Full or Limited RGB people are more likely to turn it onto Full RGB as they think they'll be getting a better image. It should really just be referred to as PC or Video levels.
Sperron, those results look like your display either renders PC/Video levels drastically differently from each other, which would be quite unexpected or, more likely, it does not support PC levels.
That is what I would expect to see from a display that does not support Full RGB, but doesn't have a hard clip at 16/235 allowing the information to be brought out with large changes in the brightness/contrast controls.