Tag Archives: Digital preservation

Behind the Scenes, Digital Collections, Digitization Expertise, Equipment, Technology

Lighting and the PhaseOne: It’s More Than Point and Shoot

Last week, I went to go see the movie IT: Chapter 2. One thing I really appreciated about the movie was how it used a scene’s lighting to full effect. Some scenes are brightly lit to signify the friendship among the main characters. Conversely, there are dark scenes that signify the evil Pennywise the Clown. For the movie crew, no doubt it took a lot of time and manpower to light an individual scene – especially when the movie is nearly 3 hours long.

We do the same type of light setup and management inside the Digital Production Center (DPC) when we take photos of objects like books, letters, or manuscripts. Today, I will talk specifically about how we light the bound material that comes our way, like books or booklets. Generally, this type of material is always going to be shot on our PhaseOne camera, so I will particularly highlight that lighting setup today.

Before We Begin

It’s not enough to just turn the lights on in our camera room to do the trick. In order to properly light all the things that need to be shot on the PhaseOne, we have specific tools and products we use that you can see in the photo below.

We have 4 high-powered lights (two sets of two Buhl SoftCube SC-150 models) pointed directly in the camera’s field of view. There are two on the right and two on the left. These are stationed approximately 3.5 feet off the ground and approximately 2.5 feet away from the objects themselves. These lights are supported by Avenger A630B light stands. They allow for a wide range of movement, extension, and support if we need them.

But if bright, hot lights were pointed directly at sensitive documents for hours, it would damage them. So light diffusers are necessary. For both sets of lights, we have 3 layers of material to diffuse the light and prevent material from warping or text from fading. The first layer, directly attached to the light box itself, is an inexpensive sheet of diffusion fabric. This type of material is often made from nylon or silk, and are usually inexpensive.

The second diffusion layer is an FJ Westcott Scrim Jim, a similar thin fabric that is attached to a lightweight stand-up frame, the Manfrotto 156BLB. This frame can also be moved or extended if need be. The last layer is another sheet of diffusion fabric, attached to a makeshift “cube” held up by lightweight wooden rods. This cube can be picked up or carried, making it very convenient if we need to eventually move our lights.

So in total, we have 4 lights, 4 layers of diffusion fabric attached to the light boxes, two Scrim Jims, and the cube featuring 2 sides of additional diffusion fabric. After having all these items stationed, surely we can start taking pictures, right? Not yet.

Around the Room

There are still more things to be aware of – this time in the camera room itself. We gently place the materials themselves on a cradle lined with a black felt, similar to velvet. This cradle is visible in the bottom right part of the photo above. It is placed on top of a table, also coated in black felt. This is done so no background colors bounce back or reflect onto the object and change what it looks like in the final image itself. The walls of the camera room are also painted a neutral grey color for the same reason, as you can see in the background of the above photo. Finally, any tiny reflective segments between the ceiling tiles have been blacked out with gaffer tape. Having the room this muted and intentionally dark also helps us when we have to shoot multi-spectral images. No expense has been spared to make sure our colors and photos are correct.

Camera Settings

With all these precautions in place, can we finally take photos of our materials? Almost. Before we can start photographing, we have to run some tests to make sure everything looks correct to our computers. After making sure our objects are sharp and in focus, we use a program called DTDCH (see the photo to the right) to adjust the aperture and exposure of the PhaseOne so that nothing appears either way too dim or too bright. In our camera room, we use a PhaseOne IQ180 with a Schneider Kreuznach Apo-Digitar lens (visible in the top-right corner of the photo above). We also use the program CaptureOne to capture, save, and export our photos.

Once the shot is in focus and appropriately bright, we will check our colors against an X-Rite ColorChecker Classic card (see the photo on the left) to verify that our camera has a correct white balance. When we take a photo of the ColorChecker, CaptureOne displays a series of numbers, known as RGB values, found in the photo’s colors. We will check these numbers against what they should be, so we know that our photo looks accurate. If these numbers match up, we can continue. You could check our work by saving the photo on the left and opening it in a program like Adobe Photoshop.

Finally, we have specific color profiles that the DPC uses to ensure that all our colors appear accurate as well. For more information on how we consistently calibrate the color in our images, please check out this previous blog post.

After all this setup, now we can finally shoot photos! Lighting our materials for the PhaseOne is a lot of hard work and preparation. But it is well worth it to fulfill our mission of digitizing images for preservation.

Behind the Scenes, Duke Digital Repository, Technology

What we talk about when we talk about digital preservation

(Header image: Illustration by Jørgen Stamp digitalbevaring.dk CC BY 2.5 Denmark)

Here at Duke University Libraries, we often talk about digital preservation as though everyone is familiar with the various corners and implications of the phrase, but “digital preservation” is, in fact, a large and occasionally mystifying topic. What does it mean to “preserve” a digital resource for the long term? What does “the long term” even mean with regard to digital objects? How are libraries engaging in preserving our digital resources? And what are some of the best ways to ensure that your personal documents will be reusable in the future? While the answers to some of these questions are still emerging, the library can help you begin to think about good strategies for keeping your content available to other users over time by highlighting agreed-upon best practices, as well as some of the services we are able to provide to the Duke community.

File formats

Not all file formats have proven to be equally robust over time! Have you ever tried to open a document created using a Microsoft Office product from several years ago, only to be greeted with a page full of strangely encoded gibberish? Proprietary software like the products in the Office suite can be convenient and produce polished contemporary documents. But software changes, and there is often no guarantee that the beautifully formatted paper you’ve written using Word will be legible without the appropriate software 5 years down the line. One solution to this problem is to always have a version of that software available to you to use. Libraries are beginning to investigate this strategy (often using a technique called emulation) as an important piece of the digital preservation puzzle. The Emulation as a Service (EaaS) architecture is an emerging tool designed to simplify access to preserved digital assets by allowing end users to interact with the original environments running on different emulators.

An alternative to emulation as a solution is to save your files in a format that can be consumed by different, changing versions of software. Experts at cultural heritage institutions like the Library of Congress and the US National Archives and Records Administration have identified an array of file formats about which they feel some degree of confidence that the software of the future will be able to consume. Formats like plain text or PDFs for textual data, value separated files (like comma-separated values, or CSVs), MP3s and MP4s for audio and video data respectively, and JPEGs for still images have all proven to have some measure of durability as formats. What’s more, they will help to make your content or your data more easily accessible to folks who do not have access to particular kinds of software. It can be helpful to keep these format recommendations in mind when working with your own materials.

File format migration

The formats recommended by the LIbrary of Congress and others have been selected not only because they are interoperable with a wide variety of software applications, but also because they have proven to be relatively stable over time, resisting format obsolescence. The process of moving data from an obsolete format to one that is usable in the present day is known as file format migration or format conversion. Libraries generally have yet to establish scalable strategies for extensive migration of obsolete file formats, though it is generally a subject of some concern.

Here at DUL, we encourage the use of one of these recommended formats for content that is submitted to us for preservation, and will even go so far as to convert your files prior to preservation in one of our repository platforms where possible and when appropriate to do so. This helps us ensure that your data will be usable in the future. What we can’t necessarily promise is that, should you give us content in a file format that isn’t one we recommend, a user who is interested in your materials will be able to read or otherwise use your files ten years from now. For some widely used formats, like MP3 and MP4, staff at the Libraries anticipate developing a strategy for migrating our data from this format, in the event that the format becomes superseded. However, the Libraries do not currently have the staff to monitor and convert rarer, and especially proprietary formats to one that is immediately consumable by contemporary software. The best we can promise is that we are able to deliver to the end users of the future the same digital bits you initially gave to us.

Bit-level preservation

Which brings me to a final component of digital preservation: bit-level preservation. At DUL, we calculate a checksum for each of the files we ingest into any of our preservation repositories. Briefly, a checksum is an algorithmically derived alphanumeric hash that is intended to surface errors that may have been introduced to the file during its transmission or storage. A checksum acts somewhat like a digital fingerprint, and is periodically recalculated for each file in the repository environment by the repository software to ensure that nothing has disrupted the bits that compose each individual file. In the event that the re-calculated checksum does not match the one supplied when the file has been ingested into the repository, we can conclude with some level of certainty that something has gone wrong with the file, and it may be necessary to revert to an earlier version of the data. THe process of generating, regenerating, and cross-checking these checksums is a way to ensure the file fixity, or file integrity, of the digital assets that DUL stewards.