To offset a channel’s values is to add a fixed value to them, which, in effect lightens the whole channel. You can also add a negative value to a channel, in which case the channel gets darker.
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| Offsetting channel values. | Offsetting channel values. |
For this effect, you use Nuke’s Add node.
| 1. | Click Color > Math > Add to insert a Add node at the appropriate point in your script. |
| 2. | Connect a Viewer to the output of the Add node so you can see the effect of your changes. |
| 3. | In the Add properties panel, use the channels field to select the channel you wish to offset. |
| 4. | Use the value slider to input the value you wish to add to the channel’s values. |
| 5. | If you are using premultiplied input images, you may want to check (un)premult by and select rgba.alpha from the dropdown menu. This simulates doing the addition before the premultiplication was done. |