will be dependant on the signal input being used; in other words, i'm not sure that you can set the proper gamma on the hdmi port, and expect it to be the perfect setting for the ota(over-the-air) tv input... for the latter, at least for now, i simply used the factory lg picture setting procedure, which also makes a good starting point for everything else.
for the hdmi port gamma setting, however, you MUST reference a standard, which i haven't seen anyone mention yet, and these are about the best i've found for setting computer monitor gamma... tv use is another subject altogether:
setting #4 to the proper 2.2 gamma is very difficult on any lcd monitor, and on my rig, these are the only settings that get close to it... you have to use the video card settings in conjunction with the monitor settings, which afaik, no one in this thread has mentioned... there is no such thing as day vs. night viewing, because setting #2 requires a darkened environment; there is only one proper gamma setting:
my nvidia gtx460 sli, "Use Nvidia settings" checked:
Aspect Ratio: Just Scan
Energy Saving: Off
Picture Mode: ISF Expert1 (or Expert2)
Dynamic Contrast: Off
Noise Reduction: Off
Digi Noise Reduction: Off
Black Level: Low
Real Cinema: Off (locked)
Color Gamut: Standard(auto-adjusts itself, depending on input)
Edge Enhancer: Off
Color Filter: Off
Color Temp: Medium
Gamma: 2.4(for me, only 2.4 would allow #4 above to be set correctly)
but setting the monitor gamma to 2.4 has a really negative effect on the black level, which is where this monitor in particular, and lcds in general, are sooo weak... i had to compensate with the video card gamma settings control.
note that all of the test graphics can be downloaded; perhaps you do a lot of photoshop, which may alter the viewing environment, vs. trying to set the gamma by viewing the same graphics in the browser? i have not explored that yet, but it makes me wonder what happens to gamma when you are trying to set it with your blu-ray player software, on your htpc... fortunately the nvidia controls give you the option of overriding the video player gamma/color controls.