Convert an image with black background to a black and white Is there a way to convert an image with a bleck background to a bleck and white so that I can use it as a mask in Cycles?
Here's the idea - From this:


To this:


I'm creating this Earth scene from "blenderguru.com" (link below) howeever, the clouds in Cycles are not visible enough and part of the clouds is fully transparent - 

Internal - 


Cycles - 


Internal material - 



Cycles material - 



I don't know what it does in the Internal, but I expect the same result in Cycles. If anyone can explain to me why do clowds are less visible in Cycles?

Earth tutorial - http://www.blenderguru.com/tutorials/create-a-realistic-earth/
to create a mask from BW image you can use this nodes :



you can change the threshold for different results