You can
simulate actual brush strokes by setting the rates at which the
brush tool strokes fade out. You can specify which options dynamically
change over the course of a brush stroke, including scattering,
size, and color. The brush thumbnail in the options bar reflects
the brush changes as you adjust the brush dynamics options.
You set brush dynamics options by selecting the brush tool and
then selecting from the following controls from the More Options
menu in the options bar.
- Spacing
-
Controls the distance between the brush marks in a stroke.
To change the spacing, type a number, or use the slider to enter
a value that is a percentage of the brush diameter. (The brush thumbnail
in the options bar dynamically changes to reflect your spacing adjustments.)

Increasing the spacing makes the brush skip.
- Fade
-
Sets the number of steps until the paint flow fades to nothing.
A low value makes the paint stroke fade away very quickly, while
a value of zero has no fading effect. Each step is equal to one
mark of the brush tip. Possible values range from 0 to 9999. For
example, entering 10 for Fade produces a fade in 10 increments.
For smaller brushes, you may want to set a value of 25 or larger.
If strokes fade too quickly, increase the values.

Fade showing setting of 40, 60, and 80 steps
- Hue Jitter
-
Sets the rate at which the stroke color switches between
the foreground and background colors. Higher values cause more frequent
switches between the two colors than lower values. (To set the colors
used by the color jitter option, see About foreground and background colors.)

Paint stroke without and with color jitter
- Hardness
-
Controls the size of the brush’s hard center. Type a number,
or use the slider to enter a value that’s a percentage of the brush
diameter.

Brush strokes with different hardness values
- Scatter
-
Brush scattering determines how brush marks are distributed
in a stroke. A low value produces a denser stroke with less paint
scattering, and higher values increase the scattering area.

Brush stroke with low and high scatter values
- Angle
-
Specifies the angle by which an elliptical brush’s long axis
is offset from horizontal. Type a value in degrees, or drag the arrowhead
of the angle icon to mark the desired angle.

Angled brushes create a chiseled stroke
- Roundness
-
Specifies the ratio between the brush’s short and long axes.
Enter a percentage value, or drag a dot in the angle icon away from
or toward the arrow. A value of 100% indicates a circular brush,
a value of 0% indicates a linear brush, and intermediate values
indicate elliptical brushes.

Adjusting roundness affects the shape of a brush tip.