" The practice of Pointillism is in sharp contrast to the traditional methods of blending pigments. Pointillism is analogous to the four-color CMYK printing process used by some color printers & large presses that place dots of Cyan (blue), Magenta (red), Yellow, & Key (black). Televisions & computer monitors use a similar technique to represent image colors using Red, Blue & Green (RGB) colors.
If red, blue & green light are mixed, the result is something close to white light. Painting is inherently subtractive, but pointillist colors often seem brighter than typical mixed subtractive colors. This may be partly because subtractive mixing of the pigments is avoided & partly because some of the white canvas may be showing between the applied dots. The painting technique used for pointillist color mixing is at the expense of the traditional brushwork used to delineate texture." Wickapedia