Compositing CGI with Bigger Node Trees - Nuke 101: Professional Compositing and Visual Effects - page 110

Let'sgoaheadandusethesepull-downmenustocombinetheLgtandColpasses.
3. Make sure Merge1's Properties panel is loaded in the Properties Bin, and view
Merge1.
4. From the A Channels pull-down menu, choose the Col channel set.
5. From the B Channels pull-down menu, choose the Lgt channel set.
6. Sinceyouneedtomultiplythetwo,changetheOperationpropertyusingthepull-
down menu at the top, to Multiply ( FIGURE 3.18 ) .
Figure 3.18. Merge1's Properties panel should look like this now.