Adjust the colour of individual channels to produce effects not easily achieved with other colour adjustment tools.
The following settings can be adjusted in the dialog:
Select a colour mode from the first pop-up menu.
Specify a single colour channel to apply the adjustment to, including the layer's alpha channel. Select from the second pop-up menu.
The sliders control the contribution of the named colour to the selected output channel. Drag the slider to the left to decrease the level of the named colour, drag the slider to the right to increase it.
Offset—controls the overall influence the selected output channel has on the image as a whole. Drag the slider to the left to decrease the output channel's contribution, drag the slider to the right to increase it.