Is what we see in the mirror a 3D image or a 2D image?

well, like a steriopticon, if you close one eye when you look in the mirror you see one thing, and if you close the other, you see something else. Seems pretty 3D to me.

I have been struggling with a related question—if a mirror in a room with only one light source, say a window, reflects that window, does the light increase in the room?

I think the answer to your q is yes… Because the source light is still producing light rays. The light rays that have already travelled to the mirror, and are now returning into the room are their own “source”. IMO

A mirror is a virtual 2d image, but in some sense or function that I do not remember at the moment it is also 3D.

I think this question will yield to Google.

oh google, you’re so strong and manly .. rip my bodice open!
I don’t remember what they are called, but there are these mirror devices that look like UFOs. If you put a small object (I saw a hershey’s kiss used) in the bottom, a “hologram” of the object appears on top. So i say 3D

3D, because one can see behind objects by moving. Can’t do that with 2D images.

here it is. You have to see the effect with stereoscopic vision though (your eyes, sorry, pirates need not apply). It doesn’t look as real through the one lens of the camera

Definitely 3D. The physics is all there, you have light paths that bounce off the mirror going to all the depths behind it, and the best evidence is that your two eyes will get slightly different images to each other.

“Resolution” is an odd term in this context. I suspect the technical term for a mirror is ‘grain’ and it would correspond to the size of the molecules of reflective material used.
Assuming it’s a ‘normal’ household mirror this reflective material is on the back side of a sheet of glass, and there are some other aspects to consider such as the clarity and flatness of the glass.
If the mirror is a “first surface” mirror and the light does not go through glass, but instead reflects right off the front surface of the mirror, then you’re in serious optical instruments territory.

The most perfect ‘mirror’ I ever had/saw/used is a silicon wafer that was rejected for making semiconductors because it was not quite flat enough. These wafers have to be flat within a few molecules. The reflection is eerie because it is so perfect and there is no distortion from going twice through a glass layer.

Definitely, 3D image. In mirror we can see our whole same scenario. Actually a live activity so, I definitely called it a 3D image in front of mirror.