Blacklevel settings

Does anyone know how to change the black level threshold so the LEDs turn off when the screen is black? Hyperion still tries to make a grey color. For example i have letterbox video and the top and bottom are out of the viewing area of the grabber. The Leds are still on. What do i need to change? thanks to anyone that can help.

thresholds dont seem to matter, Its displaying black as dim white. Id rather it just be off. any ideas?

thanks in advance

awesome ... ill give it a try. Thanks