Curve adjustments are the most precise way to alter and correct certain colour issues in images. If you are trying to alter a certain problematic area of colour, locating this on the curve can be a bit hit and miss… but of-course there is an easy way to find this out!
When you have the Curves dialogue open and have an individual colour channel selected, you can move your mouse over the image and it auto switches to the eyedropper tool (of sorts). Just click, or even click and hold on the image to see where on curve your problematic area is. It is indicated by a little circle on the curve.
Also be sure to enlarge your Curves dialogue box by clicking on the little icon bottom right of the Curves dialogue box. This makes it much easier to precisely alter the curve as it makes it bigger.
Wow, I never really played around with curves, just stuck to brightness and contrast and hue and saturation… curves rock!! Now I know how to play around with them better, thanks Jonny!
Curves are very powerful, and are quite an eye opener to many Photoshop users, thanks, glad you like the site!