Monthly Archives: January 2015

A Change of Focus

I thought I’d write about where we are with the microfilm digitization part of our project. In particular, we had a minor setback with our scanning that proved (to me, at least) to be quite educational.

We enlisted the help of The Crowley Company, a commercial digitization lab that offered state-of-the art equipment and a clean room, and that, along with experienced operators doing the work, convinced us that we would produce digital copies of these collections of the highest possible quality. But what of the microfilm itself? Were the reels in good enough condition, and was the original photography done well? We were eager to view the results, and it fell to me to analyze the scans and assess their quality.

A page selected at random from our first scanning of the a microfilm edition of the Papers of Rutherford B. Hayes
A page selected at random from our first scanning of the a microfilm edition of the Papers of Rutherford B. Hayes

How’s it look to you?

I’ll admit to having been a little unsure of myself. I explored various reels, looking for poor exposure, blurry images, anything indicating an error or gap in the digitization process. Eventually, I got a sense of what the overall resolution of the images was. But something didn’t feel right. When I looked at the top of the page (and why wouldn’t you start there?), things looked fine, but occasionally I saw things that looked blurry, and this gave me pause. Was I looking at the maximal sharpness of the image, or could things be improved? Without the microfilm on hand, I couldn’t even determine whether it was the digital photography that was to blame or the original microphotography. If the latter, there was really nothing to be done, short of re-shooting the papers, and that wasn’t an option!

Fortunately, when we had an on-site visit from Crowley, I had a chance to raise the issue with their representative. He very quickly identified a curious trend: the top of each page was crisp and clear, while the bottom was less clear. A few minutes later, he was on the phone to the scanning lab, as they still had the microfilm in their possession. At his request, the film was examined under a microscope, and we confirmed that original microphotography was in focus. This can be done ad hoc, by looking at a frame selected at random. But, fortunately, there is a more systematic method for answering questions such as these.

Resolution Calibration Test Targets Are Your Friends

When microfilm is professionally manufactured, there is a calibration chart included in the material photographed. The photographs of the chart document the focal quality of the entire batch of images. Moreover, they are designed to exhibit the limitations of any optical lens used in photography: aberration. The target looks like this:

Resolution Target Microphotograph from Reel 1 of the Rutherford B. Hayes Papers
Resolution Target Microphotograph from Reel 1 of the Rutherford B. Hayes Papers


The four seemingly redundant charts at the corners tell you something very important: how the photography resolves an image at the extreme edges of the camera lens. It’s not enough to have good focus at the center, a lens must be designed and calibrated to produce sharp images at the periphery, and these charts document how the photographic lens performed for the microfilming session. Like an eye chart, finding the smallest lines that can be resolved (and are not just a grey blur) indicates the limit of your ability to focus in on a detail in an image.

As this is a standard, highly accurate printed chart, rather than pen ink on a hundred-year old manuscript, you can get a much more reliable sense of what the photography (and subsequent scanning) captured. And here we can see the variation between a top-corner and bottom-corner chart on the very same exposure:

Upper Left Resolution Target from first scanning run (good focal quality)
Upper Left Resolution Target from first scanning run (good focal quality)
Lower Left Resolution Test Target (poor focal quality)
Lower Left Resolution Test Target from first scanning run (poor focal quality)


I find that if you examine the bars labeled “2.0”, you can see a distinct difference.  (Click on the image to expand.)

Once we’d established that at least some of our scanned reels resulted in partially out-of-focus digital images, more detective work was required. Our Crowley representative quickly established that there was a calibration error with the scanner that processed the samples we examined, and their records indicated the entire run was done with the same machine. They very quickly sent that scanner to be repaired and re-calibrated, and since they still had the microfilm on hand, they offered to rescan the material as soon as the machine was deemed fit to return to service.

We were more than happy with this arrangement. I’m hoping to use these images in an effort to extract transcripts and/or metadata from the documents photographed, and clarity is very important. Consider this side-by-side example:

The first scanning attempt:

Close-up view of text scanned in October, 2014
Close-up view of text scanned in October, 2014

And the results of recalibration:

Close-up view of text re-scanned in December, 2014
Close-up view of text re-scanned in December, 2014

I think the increase in clarity is pretty obvious (your mileage may vary!)

I’m glad we investigated this, and the turnaround time for the rescanning was excellent. So thanks again to Crowley for their diligence and expert eyes! I have a much higher degree of confidence in our digital images, and look forward to the next phase of our work.

UPDATE: The nice folks at Crowley have blogged about this project as well.


New Partners!

globe-304586_640Just wanted to do a quick check-in/shout out (!) to our wonderful partners—the ones who send us metadata and help make CPC the resource we know it can be. We’re constantly in conversations with new organizations who are interested and, if you’re reading this and manage some sort of presidential collection, that could include you!

At this moment, we’re absolutely thrilled to have officially signed on Ohio History Connection as a partner. This org is truly impressive: they serve as a technical hub for myriad historical organizations in the state, and their archival and museum programs are unique, accessible, and interesting. You’ll see their content on the CPC website in the weeks to come—for now, we’re over the moon to be moving things forward with such an impressive organization!

In Fall 2014, we added three fantastic partners:

  • UVa Press’s digital imprint, Rotunda, which includes collections from the first four U.S. presidents;
  • The National Archives’ Founders Online, another impressive collection representing material from the first four U.S. presidents; and
  • The Ulysses S. Grant Presidential Library at Mississippi State University, which brings correspondence, research notes, artifacts, and photographs from Grant’s lifetime.

Together, these collections have added more than 100,000 items to the CPC index and have expanded content available to researchers by both their depth and breadth of coverage. We’re thrilled to have them on board!

Finally, last but never least, we want to acknowledge our original partners, whose participation let us launch a robust initial site to begin with. Those are:

  • The Miller Center Oral History Program;
  • The Woodrow Wilson Presidential Library and Museum;
  • The Theodore Roosevelt Center;
  • The Rutherford B. Hayes Presidential Center;
  • The Massachusetts Historical Society; and
  • The Sixth Floor Museum at Dealey Plaza.

Should your name be on one of these lists?! Of course it should! Shoot us a note, we’d love to hear from you.