GUIDE TO MAKING ANAGLYPH 3-D IMAGES

Thousands of Civil War photographs were taken in a stereoscopic format so they could be seen in 3-D. They were the “video” of Civil War America – the photographic viewing experience that drew viewers into the depths of the photograph.

The Library of Congress owns the core collections of original Civil War documentary and 3-D photographs. More than 600 vintage, original, uncut 4×10 inch stereoscopic negatives by Alexander Gardner and his associates are kept at the library, as well as several thousand other stereoscopic negatives and prints.

Any negative with the call number prefix of B815 means that it’s a full, uncut, 4×10 inch stereo negative. Any image call number with the prefix B811 means that the image was taken in stereo but that the original single plate was cut into two halves. For the vast majority of B811 negatives, both halves the stereo image still exist.

As with nearly all Civil War images at the library, free, immediate, high-resolution downloads are available, allowing anyone to download and create their own 3-D images with all of the clarity and brilliance of the large, vintage glass plate negatives.

For the purposes of this short tutorial, let’s use the Signal Tower at Antietam. LC-B815-633, which has good stereo effect and is easy to work with.

You may find it on the Library of Congress site here: http://www.loc.gov/pictures/collection/cwp/item/cwp2003000126/PP/

Download the 44MB TIFF digital file of the full stereo negative. The key thing to remember with the uncut B815 stereos is that you must flip-flop the two images. Therefore, as you look at the raw image below, the left stereo image is on the right side of the negative and the right stereo image is on the left.

For convenience, download two high-res copies of the image and using Windows Photo Gallery or Microsoft Paint or another standard photo program, crop one to capture just the right image, which you should label “Left.” And crop the second version to capture just the left image, which you should label as “Right.”

Here is a cropped “left” image — the right side of the above negative.

Here is a cropped “right” image — which was the left side of the twin-image neg above.

Download the free program Stereo PhotoMaker here: http://stereo.jpn.org/eng/stphmkr/

Open Stereo Photo Maker, use the drop down “File” and go to second entry: Open Left/Right images. Open your image you have labeled “left”. Then go back and open the right image. They should show side by side on the screen.

Note: the above procedure works for both the uncut stereo negatives and the ones that are in separate right and left halves. Another method for the uncut negatives, the B815 series, is to download the full uncut negative. Open Stereo Photo Maker, use the drop down “File” and pick the first entry “Open Stereo Image”. This will display the full uncut stereo negative and hit the “X” key on your keyboard. This short cut will swap the right and left sides so that you now have them in their proper position. Then you just follow the rest of the steps below.

Next, go to the dropdown “Adjust” fifth from left, and drop down to “Auto Alignment” and click on that. Stereo photo maker will automatically line up both photos, horizontally and vertically, and sets what it thinks ought to be the proper stereo window.

To see it in 3-D go to “Stereo” fourth from the left, and drop down to Gray Anaglyph – Red/Cyan. Put on your Red/Cyan glasses and have a look. If you have Red/Blue glasses, or any other color combination, just pick the appropriate anaglyph method from the drop down menu. The most popular combination for anaglyphs in print and on the web is Red/Cyan.

The automatically-made anaglyph from the two cropped and aligned photos, however, doesn’t always set the stereo window properly. Think of the stereo window as a picture frame, as you look out into the scene, that picture frame shouldn’t cut off any of the surrounding objects.

You can easily adjust the window. Stereo PhotoMaker has adjustment tools. Click on the drop down “Adjust” and open the top entry “Easy Adjustment” and your working screen will show a horizontal slider above the photo and a vertical slider to the left. Using the horizontal slider, you can adjust each picture back and forth on the horizontal plane to move the stereo window. You can experiment with the horizontal settings to make the stereo look better to your eye, but be careful with big adjustments. It’s probably best not to stray too far from the automatically-set, ‘default’ anaglyph given you by Stereo Photo Maker.

The more you work with this control, the easier it is to see window violations and make pleasing anaglyphs. Look at the anaglyph below and compare with the next one. The first one just doesn’t look right and hurts the eyes. The second one, which we’ve readjusted to correctly set the stereo window, is much easier on the eyes.

When you make your anaglyph, if things look cross eyed and not right, they probably are not right. Try reversing the two images and see if that corrects the problem. It’s easy to make this mistake.

Good 3-D should never cause any discomfort or eye strain!