Adobe Photoshop CS6 User Manual page 408

Flipping a brush tip on its x axis.
A. Brush tip in its default position B. Flip X selected C. Flip X and Flip Y selected
Flip Y Changes the direction of a brush tip on its y axis.
Flipping a brush tip on its y axis.
A. Brush tip in its default position B. Flip Y selected C. Flip Y and Flip X selected
Angle Specifies the angle by which an elliptical or sampled brush's long axis is rotated from horizontal. Type a value in degrees, or drag the
horizontal axis in the preview box.
Angled brushes create a chiseled stroke
Roundness Specifies the ratio between the brush's short and long axes. Enter a percentage value, or drag the points in the preview box. A value
of 100% indicates a circular brush, a value of 0% indicates a linear brush, and intermediate values indicate elliptical brushes.
Adjusting roundness to compress a brush tip shape
Hardness Controls the size of the brush's hard center. Type a number, or use the slider to enter a value that is a percentage of the brush
diameter. You can't change the hardness of sampled brushes.
Brush strokes with different hardness values
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. When this option is deselected, the speed of the cursor determines the spacing.