This makes parts of your picture two colors: white, and the color chosen in the palette, using a dithered pattern of dots that reflect the original picture's shades; the darker the shade, the more non-white dots are drawn.
This tool offers both freehand and one-click operation.
This tool offers multiple size settings.
This tool offers color choices.
See also: Color and White & Dither (Keep Colors).
Tux Paint 0.9.34