LCD shade banding as if running lower color quality on R51

[sjthinkpader]

The machine is a R51 1836-BBU with a ATI 9000 GPU, 15 inxh SXGA+ IDTech IPS LCD. The color quality is set to 32bit color.

That bright spot in the top left of the WindowsXP boot screen appears to have bands of brightness instead of a smooth gradual shade changes. I originally thought the color quality was set too low but it was set to 32 bit color.

I then changed the LCD with an identical panel. Still banding appears. Other than that boot screen, I cannot detect any color quality issue in other screens.

Has anyone seen this phenomenon?

[Harryc]

AS far as I know, the bootscreen runs at 640x480 and you can't change that. Also I don't believe that your 32bit setting has any effect there.

[sjthinkpader]

Harry, This is the light blue welcome screen with the bright spot in the top left. Usually banding appears when set to lower color bits.

Normally that bright spot has a nice gradual shading to it. This one has the banding effect as if I had a lower color quality setting than 32 bits color.

[sjthinkpader]

More findings on this issue:

1. When this R51 is on the docking station or AC adapter, no banding can be observed.
2. When on battery only, banding appears.

Seems to be voltage dependent. Makes sense since LCD controller used voltage divider chain to get shades of gray from the LC material. When the voltage is too low, it may miss a few levels of shading