EXPERIMENTING

WITH THE 4 x 6 FORMAT

This summer (2001) we had the opportunity to visit some friends with a house in the Les Chenaux Islands along the north shore of Lake Huron. It is a beautiful area with the added attraction that the Annual Antique Wooden Boat show would be held in Hessel, MI that weekend. I dropped  my Digital Twin-Camera stereo rig in the camera bag and ended up with a collection of very nice pictures. I wanted to give our hosts a collection of stereoviews as a memento of the weekend, but they didn't have a Holmes stereoscope, so my usual Holmes stereoview option wouldn't work. While leafing through several equipment listings, I came across this familiar ad in the Reel 3-D catalog:

The viewer is intended for those 4x6 "one-hour processing" prints exposed with a beamsplitter system (attachment or Argus/Loreo camera):

This particular sample was shot with my old Pentax beam-splitter and, while it didn't turn out too badly, I really have a number of objections to the format:

• Most subjects are hard to compose with the elongated vertical aspect ratio
• Most of the systems that shoot pictures like this end up with a hypostereo effect since the mirror  spacing is usually less than the typical inter-ocular distance
• Since the pairs are "locked" onto the negative, there is no opportunity to adjust the stereo "window"

While I really don't shoot many 4x6 pictures these days, the folding viewer (shown above) does a good job and, as a potential gift item, the price is quite appealing (under $13.00). Since the viewer is designed for image pairs in the 3.5 x 5 to 4 x 6 range, the only issue was how to format the stereo image pairs to make the best use of the format. That turned out to be very easy, given the ability to handle everything on the computer.

PRINT FORMATTING

There are three possible options you may elect for getting prints made up:
 

• Use a photo-quality printer, with good quality photo printing paper, and specify a 4 x 6 inch size for each print.

• Use one of the new generation of specialized photo printers that are designed to crank out 4 x 6 prints. If you use one of these, the printer software will automatically scale your print to the proper size.

• Take your digital medium (disk, memory card, etc.) to your local 1-hour processor and have 4 x 6 prints made from your image files. The printing technology used by your processor is fundamentally different from that employed by most photo printers and will generally produce the most permanent results.

No matter which route you take, the trick is to format your image files so they will easily scale to the 4 x 6 format. If you don't, the results will often be quite strange and generally useless! The formatting steps needed to avoid this are simple once you get things set up to handle the 4 x 6 format. The first step is to decide on a uniform width for your stereo pair sets. This will depend on your image source and how the pairs are scanned. For example, I currently have three sources for my stereo image sets:
 

1. My Digital Twin-Camera system uses two small digital cameras, each with a 640 x 480 pixel image. The nominal width of a stereo pair would thus be 2 x 640 or 1280 pixels*.

2. If I use my flat-bed scanner with the film-scanning option, my Realist-format frames are scanned at 1100 x 1100 pixels, so a nominal stereo pair would have a width of 2 x 1100 or 2200 pixels*.

3. With my dedicated film scanner I scan Realist images at 2200 x 2200 pixels, so the nominal width for a stereo pair would be 2 x 2200 or 4400 pixels*.

Note that I have used the term "nominal" for each of the width calculations and have labeled the results with an asterisk. The reason is that the precise width of the final stereo pair will vary somewhat from image to image, depending precisely on how you set the stereo window. Since my most "detailed" option has a maximum value of 4400 pixels, I chose to scale all my pairs to a constant width of 4800 pixels. This is the value that I will use in the examples which follow, but you can use any value that is somewhat larger then your most detailed image format. There is no need to go to a much wider format, as that simply wastes disk space, By scaling up, I assure that I will not lose any effective resolution in any of my images. Since the H/W ratio of a 4 x 6 print is 0.6666 (4/6) and the common value for width width with my pictures is 4800 pixels, the common value for the height of my pictures will be 0.666 x 4800  or 3199.68 pixels. I rounded this off to 3200 pixels, and thus want to format my image files to 3200 (H) x 4800 (W). Using the NEW image option in your image processing/photo program, I created a blank (white) 3200 x 4800 pixel image and save it in the BMP format as card.bmp. With this file available, I format my pairs as follows:
 

• Whatever the image source, I use a stereo editing program to set up the stereo window and fine-tune the vertical alignment of the pair. Once it has been set up properly, I save the image in the side-by-side format as a BMP image - lets call it stereo.bmp.

• Using my photo software I OPEN stereo.bmp

• Using the program RESIZE function, I set the width of stereo.bmp to 4800 pixels while maintaining the original aspect ratio.

• I then COPY the resized image to the clipboard and get rid of the stereo.bmp image without saving the resized version.

• Next I LOAD the card.bmp image

• Using the PASTE function, I add the stereo.bmp image to the card from the clipboard. It will be centered automatically with most programs, otherwise I center it manually.

• Now the final image is saved, using the SAVE AS function, under whatever file name is appropriate. Whatever name is chosen, for maximum compatibility for later printing, I would save it in the JPEG format (.jpg extension on a PC) with the highest-possible quality setting (typically 100%).

The entire sequence can then be repeated for as many stereo pairs as you choose. Formatted in this fashion, the images will print out properly in the 4 x 6 format with no distortion or other problems. In the case of my Digital Twin-Camera, and various twin-camera systems with standard 35 mm digital or film cameras, the results will look like this:

Even though the actual image does not fill the print vertically, the stereoview looks just fine with the pocket viewer. In fact, having the wide borders, top and bottom, makes the prints easy to handle without leaving fingerprints that can mar the appearance of a typical "borderless" print.

If you shoot Realist-format pictures,  you can follow the basic procedures shown on my Make Your Own Holmes Stereoviews page to prepare the stereo pairs:
 
 

Despite the fact that the result is a 4 x 6-inch print, the image has the look and feel of a classic Holmes stereoview. In fact, by trimming the height to 3.5 inches, the 4 x 6 print can be pasted (literally!) to a blank 3.5 x 7 inch pice of card stock for viewing with a Holmes stereoscope. If the idea of full-color Holmes views is unacceptable, simply convert the color image files to grayscale when preparing your image sets! These prints are very inexpensive compared to the cost of time and materials for making true Holmes views and they can be stored in archival plastic sleeves/pages for 4x6 prints.

No matter what the precise format you have chosen, a label or legend can be added below either the right or left image (not both and not centered) using the TEXT function in your photo software. Since most individuals are right-eye dominant, the label will be more pronounced, when viewing, if placed under the right image.

In short, given the wide availability of 4 x 6 print viewers (not to mention their modest cost!), the print format provides an excellent option for exchanging views or providing a unique gift option, thanks to the flexibility and versatility of the Digital Darkroom!

Ralph E. Taggart (taggart@msu.edu)