HOW TO change colors of captcha image?

Jomla Captcha 2.0.0 and later

In administrator panel of Joomla! go:

Extentions -> Plugin Manager -> System - Captcha -> Parameters -> Plugin Parameters ->

Set "Text color" parameter to "0,0,0" or to "0" for black.

Set "Background color" parameter to "0,255" or to "0,255,0" for green.

etc.

The Captcha uses RGB color model