How to solve the ghosting problem?

By Andy from Digital Tiger, 12th, March. 2009, all rights reserved

What is ghosting?

Ghosting occurs when the system cannot keep up with the alternating left-right stereo images flashing on the display. The problem produces an after-image or “ghost” of objects similar to the illustration at left.
Like an unpleasant smell, users can get used to minor ghosting to the point where it becomes unnoticed. An intense ghost image, however, is a serious headache. 
 

Factors which influence the amount of Ghosting:

Persistence time of the monitor tube - the shorter the less ghosting
Contrasts within the image -  hard contrasts produce strong ghosting
LCD-quality - light blocking ratio, the manufacturers call it ‘dynamic-range’
Voltage/battery status of the glasses
Refresh rate - the higher the more ghosting !?
Brightness & Contrast setting of monitor
Parallax size
Accuracy of synchronization between glasses and monitor
Resolution
Display technique - interlace vs. page-flipping

Countermeasures:

get refresh rate down !?
get brightness up
get contrast down
make parallax smaller
use fresh batteries
use fast-phosphor projector (from Barco)
use fast-phosphor monitor (very very hard to find)
use low contrast applications and games, e.g. prefer day-scenes over night-scenarios (example: racing game, red desert, daylight, rainy weather -> almost no ghosting)

The cure for ghosting - choosing the right phosphor (July 17, 1999)

The main cause of ghosting is the slow phosphor decay time. Monitor tubes with P22 phosphors (zinc sulfide for blue/green) are very bad in this respect. Much better would be P43 tubes (rare earth for green). The problem is: P22 dominates the market. I couldn’t find a mainstream non-P22 monitor yet. 

Ghosting and  projection systems:  BARCO a leader in the large screen business is aware of the problem and offers special fast green phosphor’ versions of some of it’s 3-tube-CRT-projector models.

BARCO has an excellent page about stereoscopic 3D projection covering shutterglasses, shutterscreens, polarization glasses, single and dual projector setups with tubes and LCD. Also get the Barco color brochure on stereo projection in Acrobat Format  - a must have!

Tags:stereo,ghosting,BARCO