Originally Posted by beun
If you are around, maybe you can give some input on a decent maximum gamma curve to shoot for.
What I can do is describe what I'm using in my set-up. Progressive output DVD ran through Samsung 360 STB. Output set for 1080i. DVD looks great and off air/satellite HD looks great, some satellite feed is still a little dark even with the shadow enhance. Must look terrible without the boost down low.
Resistor feeding the diode network = 2.4K
Resistor from network to minus input of opamp = 75 ohm
Resistor from minus input to ground = 510 ohms
Opamp feedback resistor = 360 ohms
Having a pot for adjustments is a bitter-sweet thing. Changing the gamma curve is good but the gain changes, too. If it is not too late my suggestion would be to use headers connected to the different resistors and use the little two position programming shunts to set different curves.