This is one of over 4720 effects generated by Filter Forge, a Photoshop plugin that allows you to create your own filters.
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Ok, "switch" function is well understood, but seems that we can just use a checkbox if we have just 2 entries. It's enough sending one in channel 5 and the other in channel 8. This is not written in "switch help" but check it out ;)
switch, trasparent, transparent, two, 2.