Apply local adjustments with the Adjustment Brush tool

Select the Adjustment Brush tool from the toolbar (or press K).
Camera Raw opens the Adjustment Brush tool options under the Histogram and sets the mask mode to New.
Choose the type of adjustment you want to make in the Adjustment Brush tool options by dragging the slider for any of the following effects:
Exposure

Sets the overall image brightness, with a greater effect in the high values. Drag the slider to the right to increase the exposure; drag the slider to the left to decrease the exposure.
Brightness

Adjusts the image brightness, with a greater effect in the midtones. Drag the slider to the right to increase the brightness; drag the slider to the left to decrease the brightness.
Contrast

Adjusts the image contrast, with a greater effect in the midtones. Drag the slider to the right to increase the contrast; drag the slider to the left to decrease the contrast.
Saturation

Changes the vividness or purity of the color. Drag the slider to the right to increase the saturation; drag the slider to the left to decrease the saturation.
Clarity

Adds depth to an image by increasing local contrast. Drag the slider to the right to increase the contrast; drag the slider to the left to decrease the contrast.
Sharpness

Enhances edge definition to bring out details. Drag the slider to the right to sharpen details; drag the slider to the left to blur details.
Color

Applies a tint to the selected area. Select the hue by clicking the color sample box to the right of the effect name.

Click the Plus icons (+) or the Minus icons (-) to increase or decrease the effect by a preset amount. Click multiple times to select a stronger adjustment. Double-click the slider to reset the effect to zero.
Specify brush options:
Size

Specifies the diameter of the brush tip, in pixels.
Feather

Controls the hardness of the brush stroke.
Flow

Controls the rate of application of the adjustment.
Density

Controls the amount of transparency in the stroke.
Auto Mask

Confines brush strokes to areas of similar color.
Show Mask

Toggles visibility of the mask overlay in the image preview.
Move the Adjustment Brush tool over the image.
The cross hair indicates the application point. The solid circle indicates the brush size. The black-and-white dashed circle indicates the feather amount.

Note: If the Feather is set to 0, the black-and-white circle indicates the brush size. With very small feather amounts, the solid circle may not be visible.
Paint with the Adjustment Brush tool in the area of the image that you want to adjust.
When you release the mouse, a pin icon appears at the application point. In the Adjustment Brush tool options, the mask mode changes to Add.
(Optional) Refine the adjustment by doing any of the following:
- Drag any of the effect sliders in the Adjustment Brush tool options to customize the effect in the image.
- Press H to hide or show the pin icon.
- To toggle visibility of the mask overlay, use the Show Mask option, press V, or position the pointer over the pin icon.
  
  To customize the color of the mask overlay, click the color swatch next to the Show Mask option. Then, choose a new color from the Color Picker.
- To undo part of the adjustment, click Erase in the Adjustment Brush tool options and paint over the adjustment.
- Remove the adjustment completely by selecting the pin and pressing Delete.
- Press Ctrl+Z (Windows) or Command+Z (Mac OS) to undo your last adjustment.
- Click Clear All at the bottom of the tool options to remove all Adjustment Brush tool adjustments and set the mask mode to New.
(Optional) Click New to apply an additional Adjustment Brush tool adjustment, and refine it as desired using the techniques in step 6.
Note: When working with multiple Adjustment Brush adjustments, make sure you’re in Add mode to switch between them. Click a pin icon to select that adjustment and refine it.