How to render a mipmap scene at runtime using shader

Hello, we all know that there is a mipmap mode in the scene view control bar. I'd like to render a mipmap scene like that at runtime using shader. Then I can get to know which object always shows red in mipmap mode at runtime. Thus, I going to change its texture to a smaller one.
But what I can do is show the mipmap level at runtime using shader. How can I render a mipmap scene at runtime like the build-in scene in unity.

 

https://www.assetstore.unity3d.com/en/#!/content/33729
Hope you can find it useful

 

Oh, my friend, I am dealing with mipmap not minimap.
Thank you all the same.

 

Sorry for the misunderstanding