This tutorial will introduce you to the power of both of these tools. The annotated screenshot will focus on the Levels and the step-by-step instructions will give you an idea of what you can achieve with the Curves tool. So find an image you’d like to improve and let’s start manipulating its finer details.
Choose an image and click on the sidebar’s Adjustments tab. Scroll up and down all you want, the Curves tool is nowhere to be seen.
That’s because most tools aren’t displayed by default. To reveal them, click on the Adjustments pop-up menu and select Curves from the list.
You’ll be graced with a white histogram (representing all your photo’s colours), along with a line going from the lower-left to the upper-right.
Click anywhere on that curve and drag the point you’ve just created. This affects the colours (up for lighter, down for darker for instance).
You can add as many points as you need along the curve. To remove one, control+click on it and select Remove Selected Point from the contextual menu.
Just like the Levels tool, you can affect the white and black points of your image by dragging the buttons located beneath the tool’s histogram.
Alternatively, you can set your black, grey and white points with the three pipette buttons, top-right of the Curves tool. Select one to reveal the Loupe tool.
To affect a specific colour, create a custom point on the curve. To do this, click on the upper-right button then select a shade on your image.
A new point appears on the curve. Drag it around to alter the shade. Curves allow you to create very precise alterations to your photo’s colours.
Click Image to Enlarge: