Color correcting by the "numbers"

Picked up this gem from Dave Cross and I have created an action for it which I will post for download later (along with more of the actions I have created. On that note...

Copy your background layer (ctrl+J), make a new threshold adjustment layer. Drag the slider to the left, and start to drag it right slowly till you see a bit of white. Hold the shift key and click on the white spot. you have just marked the lightest point on your picture. Now do the same on the other side (move the slider to the right, and slowly pull left). You should now have two sample points on your picture (don’t click ok). Click cancel as you no longer need that adjustment layer. By the By, up in the options bar for the eye dropper tool, make sure that the sample point is on a "3 by 3" as this will give you a more accurate representation.. Now click the new layer icon to create a new layer above your current one. Hit shift + backspace to bring up the fill dialogue box. Choose fill with 50% grey and hit ok. Now change the blend mode to difference. Make another threshold adjustment layer and bring the slider to the left again. What we are trying to accomplish here is we need to find the absolute midtones of the picture. so as before slowly drag he slider to the right till you see a few white specks, this is your grey area of the picture, shift click on the spot to set a sample point. Click cancel on the adjustment layer, and trash the grey layer. Next, make a curves adjustment layer. ok, now click on the black eye dropper and find your (#1) sample point, for the point that was the darkest, and click on it, Hint...turn caps lock on and you will have a much more accurate point., next choose the lightest dropper and click on the lightest point, same for the mid tones. Click on OK, and there you have it. Toggle on and off the curves adjustment layer to see the difference. Now it is important to not that this doesn’t not work perfect for every picture, but it is still a great tip none the less enjoy!