Set the following options for painting tools in the options bar. Options available vary with each tool.

Mode

Sets the method for blending the color you paint with the underlying existing pixels. Available modes change with the currently selected tool. Paint modes are similar to layer blending modes. See List of blending modes.

Opacity

Sets the transparency of color you apply. As you paint over an area, the opacity will not exceed the set level no matter how many times you move the pointer over the area, until you release the mouse button. If you stroke over the area again, you will apply additional color, equivalent to the set opacity. Opacity of 100 percent is opaque.

Flow

Sets the rate at which color is applied as you move the pointer over an area. As you paint over an area, keeping the mouse button down, the amount of color will build up based on the flow rate, up to the opacity setting. For example, if you set the opacity to 33% and the flow to 33%, each time you move over an area, its color moves 33% towards the brush color. The total will not exceed 33% opacity unless you release the mouse button and stroke over the area again.

Press a number key to set a tool’s opacity in multiples of 10% (pressing 1 sets it to 10%; pressing 0 sets it to 100%). Use Shift and number key to set Flow.

Airbrush 

Simulates painting with an airbrush. As you move the pointer over an area, paint builds up as you hold down the mouse button. Brush hardness, opacity, and flow options control how fast and how much the paint is applied. Click the button to turn this option on or off.

Auto erase

(Pencil tool only) Paints the background color over areas containing the foreground color. Select the foreground color you want to erase and the background color you want to change to. (See Auto Erase with the Pencil tool.)