Amber and Blue Written March 22, 2009   I've been experimenting with stereo photography since 1962.  Now a new technique for presenting three-dimensional images is making a splash.  On television, it was used for a couple of Super Bowl commercials last month, followed by an entire episode of the NBC series Chuck.  Both the March 23 edition of Sports Illustrated and the March 30 edition of Time feature several pages of 3D photos.  So do their sister magazines Fortune, People, and Entertainment Weekly, part of a corporate tie-in with the March 27 premiere of the 3D movie Monsters vs. Aliens. But is it the technique all that new?  It requires wearing glasses with lenses tinted two different colors.  We've seen that before.  The new twist is that a new pair of colors is now being used, and the result looks better to people who are not wearing the special glasses.  Allow me to explain. Stereoscopy begins with two different pictures of a scene, taken from different angles.  One represents the viewpoint from a viewer's left eye; the other, from his right eye. In presenting a stereo picture to a viewer, we need to arrange somehow for his left eye to see one image and his right eye the other.  We can then rely on his brain to combine the two images to create an illusion of depth. Early stereoscopes placed the images side by side and used lenses or mirrors to focus each eye on one of the images.  However, most technologies today attempt to display both images at the same location in space, either on a printed page or on a TV or movie or computer screen. The result would be a blur as shown here, unless we have a method to block each eye from seeing the “wrong” image.  Usually that method involves special glasses. Some glasses have electronic shutters that blink on and off rapidly to allow first one eye and then the other to see the screen.  (See these examples from me.)  Others have polarizing filters to discriminate between images projected with light of two different polarization angles.  Both techniques require special displays, and neither works with a picture on a printed page. An easier alternative is to place different colored lenses in front of each eye.  This is called the “anaglyphic” method.  Its major disadvantage is that it distorts the colors of the scene, because each eye is seeing only part of the full spectrum of hues. To prepare a picture for anaglyphic reproduction, we first separate the left and right halves of the image into their primary colors:  Red-left and Red-right, Green-left and Green-right, and Blue-left and Blue-right.  By convention, the viewer will see the Red-left half in his left eye, and the Blue-right half in his right eye.  But for full color, we need to include all three primaries, so we still have to assign Green to one eye or the other. Traditionally, the Green-right half has been chosen.  When added to the Blue-right half, the result is a cyan tint. Then left and right are superimposed on the screen.  The viewer wears glasses with red and cyan lenses to separate them again.  The red lens in front of his left eye blocks the cyan light, and the cyan lens in front of his right eye keeps out the red light. However, anyone not using glasses will see annoying red and cyan fringes around some objects. Now for the new method.  Again we begin with the Red-left and Blue-right halves.   This time, however, the green that we add will be the Green-left half.  On the left side, red plus green produces a yellow tint. The viewer wears glasses with yellow and blue lenses.  Well, no, not quite.  Actually they're amber and blue, and the method is a bit more complicated than this, but my description comes pretty close. The dark-tinted amber and blue lenses block a lot of light, so using them to view these newfangled pictures is like trying to read your computer monitor while wearing sunglasses.  The pictures look rather dim, at least until your eyes have adjusted to the dark.   But the big advantage is that anyone not using glasses will observe that the fringes around some objects are now yellow and blue, and those colors are less distracting than the bright red and cyan fringes of the older method.  This is because the eye perceives little difference between yellow and white, nor between blue and black. I've used the older method to post on this website a number of 3D pictures.  They've included baseball crews and snow scenes and TCS colleagues (scroll down to Ann Crago) and a boulder and a catalpa tree. Now I’d like to present a few additional stereograms.  I've used the new method to process some 3D pictures from my archives.  Get out your amber and blue glasses, and I'll dim the lights!

Let's start with a still-life taken around 1979.  These are my parents’ chairs in the living room of our home in Richwood, Ohio. And here is my chair in my apartment in Washington, Pennsylvania, around the same time. From early 1984, here are Bob Tatrn (left) and Joe Falsetti describing a high school basketball game. I’ve aligned the left and right halves of Bob’s image, so his face has no color fringes and appears to be on your computer screen.  Joe’s two halves are offset horizontally, and the resulting yellow and blue fringes make him appear to be closer than your screen.  The fans in the background are offset in the opposite direction, so they appear to be farther away than your screen.   Early photographers learned how to take stereograms long before they learned how to take pictures in color. This black-and-white stereo view is dated May 21, 1864.  We're outside Massoponax Church in Virginia.  In the background is busy Telegraph Road between Richmond and Fredericksburg.  Union officers have brought pews out of the church to hold a staff meeting.  Gen. Ulysses S. Grant is on the left, leaning over Gen. George G. Meade’s shoulder.   Another photo shows sailors on the deck of the Union ironclad Monitor in July 1862. These stereo views are from The Civil War in Depth by Bob Zeller.  In the book, the original side-by-side pairs are reproduced.  I've processed them into anaglyphs. The stereo view above dates to 1980.  From the grounds of Trinity High School in Washington, Pennsylvania, I took two snapshots from vantage points 30 feet apart (instead of the usual three inches).  This hyperstereo effect greatly reduces the apparent size of the scene, so that the buildings appear to be mere accessories for a model railroad layout. Finally, two more pictures from 1984. Here’s Betsy Overly at work in the control room at TV3 in New Kensington, Pennsylvania. And here she is in the office, in less casual attire.

In common practice, anaglyphic pictures are often viewed without the 3D colored glasses.  This is probably the way you viewed my examples above, because you didn't have colored glasses handy.  In these circumstances, this new yellow-blue method produces a more pleasing 2D appearance than the older red-cyan method with its prominent fringes. It’ll be interesting to see whether amber and blue becomes the new standard.