A stereo image is basically a 3D image. We have seen a lot of “virtual reality headsets” in 2015( Learn more about VR here, I have a bunch of articles on VR Google VR, VR vs Hologram, Best apps for Cardboard VR, How to make a cardboard VR DIY). If we look at the phones screen without the VR set, the image we see is a stereo image. The image below is a stereo image.
When we look at an object, both of our eyes looks at the same object. Two set of images are formed, one with each eye. Then our brain manipulates and merges both images to give us a 3D view.
So, now we get an idea on how we see in 3d. Then how do we see 3D video on a 2D screen??
Well.. The basic requirement to see in 3d is to have two images one for each eye. To do this on a 2d screen, we may project a stereoscopic view( the image above is a stereo image) and separate each eyes view.
This sounds great, but doesn’t work in a movie theatre with many people.
To overcome this problem, we started overlapping the image. Ok, now how those two overlapped images are separated for each eye?
Here comes the Polarised glasses. Both the overlapped images on the screen are polarized in a different way, each lens on the glasses are used to match the respective polarization. There we go, we have one image for each eye. But if we look at the image without glasses, the image looks something like this;)
This is how we experience 3D:)