Why did 3D TVs have to be specifically designed for the effect instead of the DVDs?

Question

I remember magazines were printed with a specialized pattern (red and blue ink) that made them work with 3D glasses. What tech is used in the TVs that can’t just be used in the movies themselves?

In: Technology

Answer 1

Your two eyes view two slightly different angles of the same object. Your brain combines these two different perspectives into one image with depth perception. 3D images work by sending different images to your left and right eyes in order to give the illusion of depth. In order to give your left eye the left perspective, and your right eye the right perspective, the thing displaying the content must have some control over which eye sees which image.

With the old red and blue (or red and green) 3D, the two perspectives of the drawing were printed with two colours, and tinted glasses filtered specific colours to the correct eye where your brain would merge the drawing into one image with depth.

With Active 3D, which is what u/cttttt described, the TV would alternate displaying frames of the left and right perspectives, and would sync up with a set of powered LCD shutter glasses which would make sure each eye only saw the correct frames.

With Passive 3D, which later 3D TV models used and is also used in cinema, two different types of polarisation were used on the projected image, which the polarised glasses filtered for the correct eyes.

VR is more direct. The headset has separate screens for the left and right eye, and displays different perspectives for each eye.

The core concept of all of these is the same: specific images must be shown only to a specific eye. If the left eye views the right perspective or vice cersa, the depth illusion doesn’t work, it just looks like a blurry image. There’s no way to achieve this simply by changing the content (whether that be a downloaded video, a DVD, BluRay, projector etc). The output device must have some mechanism to display the different perspectives, and ensure the correct image is only seen by the correct eye. The content of course also needs to actually contain the two perspectives, and send them to the output device in a way the device understands.