In the Paint Panel or Brush Options window increase the contrast between strokes by adjusting Sharpness and Sharpen Strength.
Controls the amount of sharpening. The valid range is 0 (no sharpening) to 10 (maximum sharpening).
By default, the Sharpen brushes have a Sharpen Strength value of 1.5. You may want to increase the Sharpen Strength to make the image or strokes harder or more defined, or reduce the Sharpen Strength to add importance to some edges without calling too much attention to them.
To set Sharpness and Sharpen Strength
In the Paint Panel or Brush Options window, adjust either the Sharpness or Sharpen Strength slider or enter a value in the Sharpness or Sharpen Strength field.
See also Sharpen paint.