Editing 3D display (section)

==== Active shutter systems ====
{{Main|Active shutter 3D system}}
[[File:Xpand LCD shutter glasses.jpg|thumb|A pair of LCD shutter glasses used to view XpanD 3D films. The thick frames conceal the electronics and batteries.]]

With the eclipse method, a shutter blocks light from each appropriate eye when the converse eye's image is projected on the screen.  The display alternates between left and right images, and opens and closes the shutters in the glasses or viewer in synchronization with the images on the screen. This was the basis of the [[Teleview]] system which was used briefly in 1922.<ref name="Amazing15-16">Amazing 3D by Hal Morgan and Dan Symmes Little, Broawn & Company (Canada) Limited, pp. 15–16.</ref><ref name="3dmovingpictures.com">{{cite web |url=http://www.3dmovingpictures.com/chopper.html |title="The Chopper", article by Daniel L. Symmes |publisher=3dmovingpictures.com |access-date=2010-10-14 }}</ref>

A variation on the eclipse method is used in [[LCD shutter glasses]].  Glasses containing [[liquid crystal]] that will let light through in synchronization with the images on the cinema, television or computer screen, using the concept of [[alternate-frame sequencing]].  This is the method used by nVidia, [[XpanD 3D]], and earlier [[IMAX]] systems.  A drawback of this method is the need for each person viewing to wear expensive, electronic glasses that must be synchronized with the display system using a wireless signal or attached wire.  The shutter-glasses are heavier than most polarized glasses, though lighter models are no heavier than some sunglasses or deluxe polarized glasses.<ref>{{Cite web|url=http://www.berezin.com/3d/samsung_3d.htm|title=Samsung 3D|website=www.berezin.com|access-date=2017-12-02}}</ref> However these systems do not require a silver screen for projected images.

Liquid crystal light valves work by rotating light between two polarizing filters. Due to these internal polarizers, LCD shutter-glasses darken the display image of any LCD, plasma, or projector image source, which has the result that images appear dimmer and contrast is lower than for normal non-3D viewing. This is not necessarily a usage problem; for some types of displays which are already very bright with poor grayish [[black level]]s, LCD shutter glasses may actually improve the image quality.