Missing threshold in the post processing section There is no threshold under the post processing title for my current working file. If I open a new file, threshold appears as in right picture. It seems that I've changed some settings but I couldn't find. What can be the reason of this situation?

Note: I think this is related to settings, not objects, because I took the screenshots for newly added object in both files.
This panel changes depending on if your render engine is set to Cycles or Blender Render in the info bar at the top of the Blender window:



You have probably changed the render engine to Cycles in your current file, but in the new file it goes back to the default Blender Render.