EyeonTips:Manual/Fusion 6/Channel Boolean

From VFXPedia

On the Color Channels tab the tool controls are divided as follows:

On the left side are target channels for the image piped into the Channel Booleans (Background input). The dropdown to the right lets you choose whether you want to modify the BG image with its own channels (suffix BG after list name) or with the channels from another image, which must be piped into the Foreground input on the Channel Booleans node (suffix FG in the drop down list).

Examples

To replace the existing alpha channel of an image with the alpha of another image choose 'Do Nothing' for To Red, To Green, To Blue and 'Alpha FG' for To Alpha. Pipe the image containing the alpha into the Foreground input on the Channel Booleans. Operation: 'Copy'. The same operation can also be performed using the Matte Control tool.

To combine any type of mask into an alpha for an image choose 'Do Nothing' for To Red, To Green, To Blue and 'Matte' for To Alpha. Pipe the mask into the Foreground input on the Channel Booleans. Operation: 'Copy'.

To subtract the red channel's pixels of another image from the blue channel choose 'Do Nothing' for To Red, To Green and 'Red FG' for To Blue. Pipe the image containing the red channel to subtract into the Foreground input on the Channel Booleans node. Operation: 'Subtract'.