The convolve tool uses the current brush to blur or sharpen your image.
See also: Brush Selection .
The Opacity slider sets the transparency level for the operation. A higher opacity setting results in a more opaque render and a lower setting results in a more transparent one.
The Pressure Sensitivity section sets whether hardness, rate or size will be effected by pressure for input devices that support this option.
The rate slider sets the strength of the convolve effect.
Blur mode blurs the image colors into each other. The result will be a smooth transition between colors, but will always be darker than the original colors.
Sharpen mode causes neighboring pixels with similar colors to converge. Used judiciously, blurry edges can be sharpened somewhat, but if applied repeatedly it can produce unusual results.
Default Keyboard Shortcut: V
Ctrl will switch between blur and sharpen modes. The mode will remain switched until Ctrl is released.
Shift places the convolve tool into straight line mode. Holding Shift while clicking Button1 will convolve in a straight line. Consecutive clicks will continue convolving in straight lines that originate from the end of the last line.