My VGA shield for the A20-OLinuXIno-LIME2 (and one question about VGA output)

[ejsanyo]

Hello everybody.

Some time ago I made a homebrew PCB to take a VGA output from this board. I believe that the logic inverters schematics is more efficient compared with the discrete transistors based like it was in the A20-OlinuXino-MICRO.
There is a drawing of this shield, maybe it will be useful for someone: https://yadi.sk/i/4rXUP2E23KG6zL
There are gerbers of the shield: https://yadi.sk/d/D0rCo_u63KG7i2 Keep in mind that position of connectors XS1 and XS2 is critical. Also it's important to have inverter with T index because of it's 3.3V logic compatibility (74ACT series, but 74HCT must be fine as well).

Some photo of the result:


And about my question: I noticed the VGA picture is slightly overexposed, so to speak. This is most noticeable in the light areas of the image:


It looks like the RAMDAC was not turned properly. I beleive it must be some software for the A20 SoC that can make a gamma correction and change other image parameters. Do you know anything about this?