Custom Channel Data from Bitmap

[AndyMurdock]

Custom Channel Data from Bitmap

I can use a scale op to take a bitmap's gray scale values and set the scale. That is easy. 
How do I take a bitmap's gray scale value and put those values in a custom channel for other purposes?  For instance: I'd like to drive the animation time of an actor with the gray scale value from a surface the particle sit upon. Could we have a way to pick a surface and texture map, grab a value and then set a custom channel value?
Or is there already a way to do this? 

[tyFlow]

You can use a Surface Test operator, and just save the values by enabling the relevant option in the Test rollout.

[AndyMurdock]

You can use a Surface Test operator, and just save the values by enabling the relevant option in the Test rollout.

Yes, Surface test > Test Type Texture > Save all test values to channel. 
That did it, thanks. 
A