In the Curves adjustment, you adjust points throughout an image’s tonal range. Initially, the image’s tonality is represented as a straight diagonal line on a graph. When adjusting an RGB image, the upper-right area of the graph represents the highlights and the lower-left area represents the shadows. The horizontal axis of the graph represents the input levels (original image values) and the vertical axis represents the output levels (new adjusted values). As you add control points to the line and move them, the shape of the curve changes, reflecting your image adjustments. The steeper sections of the curve represent areas of higher contrast while flatter sections represent areas of lower contrast.

You can save Curves adjustment settings as presets. See Save adjustment settings and Reapply adjustment settings.

Adjust image color and tone with Curves

Moving a point in the top portion of the curve adjusts the highlights. Moving a point in the center of the curve adjusts the midtones, and moving a point in the bottom section of the curve adjusts the shadows. To darken highlights, move a point near the top of the curve downward. Moving a point either down or to the right maps the Input value to a lower Output value, and the image darkens. To lighten the shadows, move a point near the bottom of the curve upward. Moving a point either up or to the left maps a lower Input value to a higher Output value, and the image lightens.

Removing control points from a curve

To remove a control point, do any of the following:

• Drag the control point off the graph.
• Select the control point and press Delete.
• Ctrl-click (Windows) or Command-click (Mac OS) the control point.

Set Curve display options

You can control the curve grid display using the Curve display options.

Apply an Auto correction in Curves

Auto applies an automatic color correction using the current default setting. To change the default setting, choose Auto Options from the Properties panel menu and set the options in the Auto Color Correction Options dialog box. You can apply an Auto Color, Auto Contrast, or Auto Tone correction to an image. For more information on these options, see Set Auto adjustment options.

Set black and white points using the black point and white point sliders

When applying a Curves adjustment, use the black and white sliders to quickly set the black and white points (pure black and pure white values) in the image.

Add contrast to the midtones of a photo with Curves

If the image uses the full tonal range, but needs midtone contrast, Click the Curves icon  in the Adjustments panel. Drag the curve into an S shape.

Keyboard shortcuts: Curves

You can use these keyboard shortcuts for Curves:

• To set a point on the curve for the selected color in each color component channel (but not in the composite channel), Shift+Ctrl-click (Windows) or Shift+Command-click (Mac OS) in the image.
  
  

• To select multiple points, Shift-click points on the curve. Selected points are filled with black.
  
  

• To deselect all points on the curve, click in the grid, or press Ctrl‑D (Windows) or Command-D (Mac OS).
  
  

• To select the next higher point on the curve, press the plus key; to select the next lowest, press the minus key.
  
  

• To move selected points on the curve, press the arrow keys.
  
  

• (Curves dialog box) To set a point on the curve for the current channel, Ctrl-click (Windows) or Command-click (Mac OS) in the image.