Adobe Photoshop CC 2014 v.14.xx - Manual (Page 658)

Drawing or painting with a graphics tablet
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Note:
Change brush size and opacity with pen pressure
If you work with a graphics drawing tablet, such as the Wacom® tablet, you can control painting tools with pen pressure, angle, rotation, or the
stylus wheel.
1. Select the Brush , Pencil , or other painting tool.
2. In the options bar, do either of the following:
Click the Tablet Pressure Controls Size button .
Click the Tablet Pressure Controls Opacity button .
Choose Window > Brush to access additional controls that vary the angle, flow, scatter, texture depth, and roundness of the stroke
according to pen pressure.
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