Glossary

Anaglyph- A two-color 3D method, requiring you to wear glasses- usually red and cyan (light blue). This method is limited by the obvious color renderings of the pictures.

Baseline- The distance you move between the left and right pictures when taking them.

Charge-Coupled Device, or CCD- A semiconductor element that measures the intensity of light falling upon it.  It outputs a voltage proportional to the intensity of that light.  In a digital camera, CCD's are arrayed in a rectangular shape to capture an entire image at once.  In a scanner, they are a linear array that is then scanned across the image, capturing one line at a time.

Cross-eyed free-vision fusion- A method of viewing 3D pictures where the left eye's image is on the right, and vice versa. You cross your eyes so that the left eye looks at the image on the right and the right eye looks at the image on the left. You must force your focus back out to the pictures. This works for larger images than the wall-eye (or parallel) method will allow.

Field of View- Usually measured in degrees, this is the angle that a lens can accept light.  For instance, the human eye's horizontal field of view is about 175°.

Flatbed Scanner- Any scanner with a lid and a large piece of glass that allows you to lay basically any object on it.  There are also drum scanners, slide scanners, and other smaller format photo-feed scanners that aren't conducive to ad-hoc stereo imaging of objects around the house.

Free-Vision Fusion- The ability to view 3D images without the use of optical aids. This can be achieved with either the cross-eyed method or the wall-eyed method.

GIF- Graphic Interchange Format.  Invented by CompuServe, it's the other main graphic format of the web.  Disadvantages are a 256-color palette (i.e., no true color), and advantages are transparency- the ability of non-rectangular images to seamlessly blend in with background items on a web page.  Also, GIFs allow for short animations.

HTML- HyperText Markup Language.  The stuff that makes web pages what they are.

Hyperstereo- Using a baseline that is greater than the distance between the left and right eyes when taking the pictures. This exaggerates the stereo effect, making the objects look smaller, like a train set or an architects model. This is the method by which I take most of my stereo pictures. It is, in my opinion, the best method for outdoor stereo photography.

Hypostereo- Using a baseline that is less than the distance between the left and right eyes when taking the pictures. This exaggerates the size of the objects, making them look larger than life. A good use for this would be 3D photographs of small objects- one could make a train set look life size.

ISO- International Standards Organization which set the standards for film speed. Typical speeds are 100 for normal outdoor daylight usage. Higher speeds (200, 400, etc...) are faster, but usually suffer some in color and grain, or resolution. Slower speeds (25, 50, etc...) have much better grain and color, but need more light or more exposure times, sometimes needing a tripod.

Java- An object-oriented, platform independent language developed by Sun Microsystems.  All browsers have a Java Virtual Machine installed that interprets the Java "byte code", or intermediate instruction format, and converts it to instructions that your machine understands, whether it's an Intel-based machine, Unix-based, or other.  Java is needed by this site in order to view the JPS images, as I use Andreas Petersik's Java Stereoscopic Applet.  You can enable and disable Java in your browser preferences.

Javascript- Not related to Java, it is a scripting language that most browsers also understand in addition to HTML.  This site uses Javascript in a limited way to provide for animation, or "rollover" effects, on the front page when you move the mouse over the graphics.

JPEG- Joint Photographic Experts Group.  An image format that drastically reduces image size, at the expense of throwing out information.  Most of the time, the loss of information is not noticeable.  When saving an image, you can set the degree of compression you would like, at the expense of image quality.  Usually, you can achieve 3:1 compression without noticing much.  JPEG uses an 8x8 grid and does a discrete cosine transformation on the image.  The result when compression is high and quality is low is a tiling patter and visible artifacts at high-contrast boundaries, particularly noticeable in skies.

JPEG2000- A newer, more computationally intensive JPEG standard.  It allows for much higher compression rates than JPEG for comparable image quality loss.  To achieve this, it uses a wavelet transformation on the image, which takes much more computing power, but as time progresses and machines become faster, this is less of a problem than when the first JPEG standard came out.  The size of the compressible area can vary, so no tiling pattern is evident.  In extreme compression, I've noticed artifacts orthogonal to the boundaries of features.  I will support this image format at some time in the future when most browser have been upgraded to support it.  Most likely it will be some time after 2001.

JPS- JPEG Stereo image.  This is a variant of the JPEG image standard that contains two images.  JPS compliant viewers then can extract those images and display them in a number of user-friendly formats, such as Anaglyph, Cross-eyed, Parallel, or for LCD Shutter Glasses.  Examples of viewers include Nuvision 3D Plug-in, DepthCharge Plug-in, and the Stereoscopic Java Applet, by Andreas Petersik.

LCD- Liquid Crystal Display.  An electrically-activated material that is composed of a crystal with a polarizing material on each surface.  When an electrical charge is applied to it, the crystal twists 90°, thus blocking light transmission, just like two camera polarizers would do when at right angles to each other.

Lenticular screen- A projection screen that has embossed vertical lines for it's finish rather than the "emery board" finish most common. They tend to cost more. The silvered version is critical to 3D projection, as any white screen will not preserve the polarization of the image reflected off it.

Parallel free-vision fusion- A method of viewing 3D pictures where the left eye's image is on the left, and the right eye's image is on the right. It works with small images, but I think it is somewhat limiting on a computer screen.

Pixel- Abbreviation for Picture Element.  The basic unit of an image on a computer or in a CCD.

Plug-in- A term for a computer program that operates from within the confines of your application- in this case your Netscape or Internet Explorer browser window.  They serve to extend the functionality of the browser- in this case, allowing the browser to seamlessly display images of a different type than standard.  Only a few of the more popular plug-ins are included in your browser installation, and the one you need for this site is probably not there, but can be downloaded and installed easily by the user.

SLR- Single Lens Reflex.  This type of camera usually has detachable lenses and lets you view through the lens the scene you are photographing, rather than through a non-boresighted viewfinder, which are usually not accurate at close distances when framing your shot.

Shutter Glasses- A device worn on your head, with two lenses generally covered in a liquid crystal material (LCD) and controlled by your computer.  When viewing a 3D image using these glasses, your computer displays the left image first, while instructing your glasses to open the left eye's "shutter" (making the liquid crystal transparent) and to close the right eye's "shutter" (making the liquid crystal opaque).  Then in a short interval- 1/30 or 1/60 of a second, the right image is displayed, and the glasses are instructed to reverse the shutters.  This keeps up for as long as you view the image.  Since the time interval is so short, your brain can't tell the difference in time, and views them simultaneously.

Stereogram- Also called a Random Dot Stereogram. This is a method in which a pattern is repeated at about the distance between your eyes (2.5-2.75 inches). Minor variations in the patterns from column to column will combine to give you depth information when your eyes have diverged from their focus point (relaxed focus- walleyed). This method has limitations due to the fact that only graphics-type images can be shown- not a true-color image.

Twain- Image acquisition device driver standard.  Most imaging devices provide a Twain interface that allows most image editing software to directly acquire images from that device.  More than one imaging device can be connected to your computer.  Twain is not an acronym, it is just a name.  For more information, go to the official Twain web site.

USB- Universal Serial Bus.  A hot-pluggable new interface on computers.  It allows the user to just plug the device in and use it.  Many scanners now support USB, as does the QX3 Microscope.

Wall-eyed free-vision fusion- See Parallel free-vision fusion.

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