Viewing Stereo Images on a Computer
There are a variety of methods to view stereo images on computer monitors. We
will go over the easiest to adapt to home use and will not discuss the more esoteric
albeit impressive methods.
Wall Eyed or Parallel Viewing
To produce a stereo image a left and right image is needed. The easiest method is
to place the stereo pair's left image on the left, and the right image on the right
side of the screen. This can be free viewed if the image is not too large and the
user is able to maintain proper control over their eyes. This requires a bit of
training and for most casual viewers cannot be done easily. Some optical viewers for
looking at stereo cards (prints) work for images displayed this way. We offer the stereo card viewer for images of around 8" or less per pair,
the View Magic 6 x 6 and our Hyper-View viewer for larger
images. Standard unmodified stereoscopes generally don't work because the tongue
which holds the card on the viewer does not allow the viewer to get close enough to the
screen to focus.
A new variant is the ScreenScope. This
has a fixture which attaches the mirrored viewer to the computer and allow
viewing without the aid of shutter glasses which allows it to work on a laptop
computer.
Cross Eyed Viewing
Placing the images right view first followed by the left view allows the user to free
view using the cross eyed method. This is easier for most people than parallel
viewing but there is no viewer available which will allow people who cannot freeview to
look at these images. Many web sites present their images in a left/right/left
format three photos across in order to accommodate both freeviewers and people with
viewers.
Over-Under
Special mirrored viewers are made for over/under format. The most
common one is
the View Magic. Over/Under format involves using a
mirror system to separate the left and right images which are placed on top of one
another. The mirrored viewer can be held parallel to the monitor for best results.
Anaglyphs
Another method is to convert a computer image into an anaglyph. The separate left
and right images are color converted so that only one of the image can be viewed through a
corresponding color gel. They are then put together on the same image base allowing
the channels to be separated later by the viewer using so called 3d
glasses (usually red/blue or red/green). This can be done using PhotoShop or any
other advanced image editor. These can also be achieved using some of the computer programs
and applets mentioned below.
The advantage to this is no special applet or program is need, just anaglyph glasses.
The disadvantages are that this method generally does not reproduce color well.
The color filters can interfere with the colors present in a scene and high
contrast in the initial image can cause significant ghosting. Skillful editing can
limit this but it generally does not entirely eliminate the problems. With grayscale
images these problems are much less apparent. Also the viewer needs the 3D glasses
to view the images.
Shutter Glasses
In the last 5 years commercially available shutter glasses have come down in price so
they are available to the consumer for well under $100. These glasses generally work
by using LCD crystals turning on and off coinciding with the alternating left and right
images on the computer screen. They can be limited by the resolution and refresh
rate of the monitor/videocard set up. They have the advantages of better
reproduction of color than anaglyphs. Generally they do not work on laptops.
