Color Mode Validation

Hi, 

We are trying to find a way to query a given output's color mode. It, however, is not obvious on how to do that, because the output inherits its color mode from its input. In the previous approach that we tried, we were assuming that there was a bitmap feeding into that channel, but we learned that it is not always the case. Ideally, we don't want to have to traverse the graph upstream from the output node at all. Is there is a direct way to query the output color mode? Thank you!