Digitizing in Twenty Colors

By: Laura Bandy

Last month, CSNTM trained more of its staff on a device originally developed by NASA for satellite images—a camera that uses MSI. What our staff spent the better part of a week learning, we want to share with you (in an abbreviated form, of course). 

What is MSI?

MSI is multispectral imaging. Unlike a typical digital SLR (single-lens reflex camera) that your family photographer might use that takes photos in natural light and with objects in motion, an MSI camera takes several different captures—one color at a time.

If your family had to sit still for twenty different shutter clicks, can you imagine how long one picture would take? When we measured one round of images with our camera, each complete photo took more than two minutes to capture. Of course, the manuscripts must remain extremely still, or the images—once compiled—will look blurry.

So why go through such trouble? Why shoot photos with an MSI camera instead of an easier-to-use, high-quality DSLR?

A DSLR camera might have 12 megapixels ready to absorb light waves. But the 12 megapixels are divided into three groups of color receptors: red, green, and blue. A pixel that knows only to absorb red light “ignores” green light. So, for all the red pixels dispersed throughout the camera’s sensor, blue or green light will skip over those pixels. But with a hard-working little computer involved that knows how to assume the change in red throughout the image, the camera can guess what amount of red would have actually existed at that pixel. This explains why your family photographer paid thousands of dollars for a DSLR camera to produce stunning colors—and why your family doesn’t need to pose for two whole minutes.

But if an organization or research institution uses an MSI camera, they aim to produce more than just a “pretty” picture. They want facts

Measuring the specific amount of blue in a manuscript’s ink can reveal the chemical compound of the ink the scribe used. And if a researcher can find out the type of ink, he or she may also discover the production location or age. An MSI camera records practically perfect measurements of various colors in an object—whether amber, blue, ultraviolet, or even infrared—depending on which single-colored lights the digitizers decide to use. Software can then compile each different monochrome photograph and construct a composite image. 

An MSI camera, then, takes only monochrome photos, and digitizers have to capture one color photo at a time. Unlike a typical DSLR camera with its designated red, green, and blue receptors, an MSI camera can gather the exact color value hitting every single pixel at the moment the shutter opens and a photo is taken—but only as long as one color shines at a time. 

The pictures below show CSNTM using specific, monochrome lights in order to gather data for twenty different colors.

What tasks can CSNTM use it for?

CSNTM’s MSI camera images can provide extremely accurate data, precisely counting the reflection of light waves and giving us much-needed information about a New Testament manuscript. But the MSI camera can do even more than that. A manuscript’s ink, pages, and other markings can react to light waves invisible to the human eye—such as infrared rays—and an MSI camera can interpret the frequency of those infrared light waves. In doing so, it can reveal undertext and watermarks.

An old French Bible CSNTM used during its MSI training looked like it had a watermark on its last page, but the staff was unable to discern the paper-making company’s name or design, which could give us a date for the book. So, we tried our new skills on the last page to see if we could take a clear image of the watermark. Below are images from before and after our MSI digitization.

What does CSNTM want to do with MSI?

CSNTM is preparing for expeditions to gather crucial information like what we uncovered with the old French Bible, only from even older and more fragile New Testament manuscripts that hold many secrets. With infrared and UV images and precise color data, New Testament textual scholars expect to obtain dates, read hidden text, and gather other vital information. We are excited to share these discoveries with you soon and are grateful for your dedication to the preservation and scholarship of the New Testament text.