This  tool lets you draw on the paint object  by painting on it using the Paint color include Mono color gradient color or image. To use this tool, simply select it from the Tool panel then draw directly on your image (you have to select an paint object first before you can start drawing).

     Adjust the opacity level  curve  of the Paintbrush Tool to control the opacity  change of the brush, the more the color is transparent therefore showing more of the base image.