Camera Raw Tone Point

Tone Point

While in the Tone Curve Dialog box, and with the Point tab selected, click on the drop down list to the right for Curve. You'll notice four options that you have to work with. The first option, linear, will give you your basic default "no adjustment" setting. Medium Contrast will bump up your contrast a little bit and then Strong Contrast will continue to bump up the contrast even more.
The Custom option will basically give you the option of manipulating the curve and setting your own points on it, just like you are able to do so within photoshop using the Curves adjustment layer. Feel free to play around with the Custom one and set a few points. Remember that for most cases just a suttle change will do the job. The Custom option gives you total control of your mid tones, highs and lows.

*End Tutorial*