I own a TC-P55GT50. I'll post my settings from my Amazon review for you here. I hope this helps. It seems to me there isn't much difference between the ST and GT series. Mostly marketing.
4 Weeks Later...
I lowered the Panel Brightness from "High" to "Mid". This helps to improve the shadow detail. Gamma control higher than 2.2 crushes the blacks and shadow detail. I keep mine on 2.0. I reduced the Sharpness from +13 to +8 to reduce the side effect of ringing.
Settings:
-Picture Menu:
Picture Mode: Custom,
Contrast +86,
Brightness +58,
Color +38,
Tint +0,
Sharpness +8,
Color temp: Warm 2,
Color Mgt: Greyed out,
C.A.T.S: Off,
Video N.R. Auto,
Pro settings submenu:
Color Space: Normal,
W/B high R: -2,
W/B high G: 0,
W/B high B: 0,
W/B low R: +1,
W/B low G: -7,
W/B low B: -2,
Gamma Adjustment: 2.0,
Panel brightness: Mid,
Contour Emphasis: ON,
AGC: 0,
-Aspect Adjustment submenu:
Screen Format: FULL,
HD: Size 2,
H size: greyed out,
Zoom Adjustment: GREYED OUT
HDMI Settings: no change,
-Advance picture submenu:
3D Y/C filter: greyed out,
Color Matrix : greyed out,
Block NR: greyed out
Mosquito NR: ON,
Black Level: Light,
3:2 pulldown: greyed out,
24p Direct in: greyed out,
