Changing gamma, contrast, colour, saturation etc via "echo" in "autostart.sh"

Hi,

Does anybody know the values that can be changed to control colour, contrast, gamma etc in the Rockchip RK3328 system files? I'm happy with RK overall, but I find the picture can be a little flat. I don't really want to change the settings on the TV as I have them setup so that one setting works well for all kinds of devices - it's just that the rockchip RK3328 box I have is lacking some punch in video playback.

I've looked on the net but can't find any pointers. I was hoping I could use "echo" <some value> to some system file(s) and add these to "autostart.sh" on LE in the RK3328 box. That way, only that box would be affected by the changes.

Does anybody know where the settings are stored? Maybe Kwiboo knows?

Thanks for any help that can be given.