3D glasses are required to view three dimensional content displayed on 3D HDTVs. 3D glasses use LCD active shutter technology. 3D DLP Link glasses uses white light synchronization when used with DLP (digital light projection) televisions. 3D IR (infrared) glasses use adapters and emitters for synchronization. Unlike passive polarized 3D glasses and old fashioned anaglyph 3D glasses, active shutter glasses produce high-resolution, high-contrast images that are bright and cause less viewing discomfort.