Absolute Color is based on a hue wheel subdivised into 6 sectors of 60 degrees. Choose a sector to restrict the tints of the image to this one.
(Information from the web site:http://www.mehdiplugins.com/english/absolute.htm)
This filter has two options:
When this option is checked, the luminance is protected. However, when it is unchecked, the plugin does not make any calculation!!! The three values r,g,b of each colors are just sorted out according to the chosen sector. Recommendation: leave marked.
Let's suppose that you chose the yellow-red sector. If you mark this option, the red tints will be inverted with the yellow tints.