How to selectively blur specific objects without affecting others? I have have 2 objects emitting different colors of light.  I want to give a blur effect only for Object-1.  But when I composite, blur is applied to both of the objects. So, would anybody here mind telling me how to add filters for particular object in same scene and same layer?

Thanks in advance.
If you have objects on one render layer, there is only one useful method: using Object ID or Material ID. 

Set a number more than 0 in material settings:



or in object data:



And on object Index/material Index pass in render layer:



You can use this pass by ID mask node. Index in node settings must by equal to number entered before in object or material settings.