If you want to paint using colors, but you know your finished painting will be viewed in black and white (on paper or on monochrome displays), you can map each color to a choice of black, white, or transparent. This can help make the black and white image easier to view.
buttons at the bottom of the Color Picker
to map colors.
The three small buttons contain the colors you can map to:
black, white, and transparent, respectively.
To the left of the buttons, the color you are currently
mapping is displayed.
To map colors: