Performing Quality Review of Digital Images

This is a guest post written by Katie Daughtry, Digital Library Technician in the Preservation Services Division.

The Reformatting Projects Section (RPS) in the Preservation Services Division reformats collection materials in order to preserve the information found in at-risk materials and to allow access by researchers. General Collections books that are crumbling and contain highly acidic paper are one type of at-risk items that RPS works with. Specialized equipment and cameras are used to capture images of the books and create digital objects that are both accessible to the public and preserved in long-term storage. Some of this work is completed in-house using our Digital Transitions BC-100 book scanner, however the majority is completed via contracts with vendors. Whether the item is digitized in-house or is transferred to a vendor, an important part of RPS’s work is performing quality review of the digital objects in order to ensure that images meet quality standards.

I began my career at the Library of Congress as the Librarian-in-Residence for the Preservation Directorate in May 2020, and have since been hired to a permanent position as a Digital Library Technician in the Reformatting Projects Section. Performing quality review of images has made up a portion of my work in both positions and has served as a useful at-home activity while telework has been optimized during the COVID-19 pandemic. Follow along as I take you through the process of performing quality review of brittle books that have been digitized by a vendor.

When a vendor makes a delivery of digitized content the files are ingested and made available on Sampler, the library’s home-grown tool for reviewing digital content. The size of the sample set, anywhere from 10% to 100%, is determined before the project starts and can be adjusted later if needed. The master files and derivatives are delivered in Bag-It structure with specified metadata and these bags are either accepted or rejected by staff within Sampler.

List of bags available for review in Sampler. Photo credit: Katie Daughtry

The first step I perform during quality review is to pick an un-reviewed bag. A bag typically contains images in tiff, JP2, and PDF file formats. First off, I open a grid view of JP2 images is to check that images look like they conform to image quality guidelines. Some errors can be obviously seen via the thumbnails. Some or all of the JP2 images can be also be selected to view the image at full-scale to ensure it meets quality standards. The next step is to open the PDF file to check for completeness, image quality, and test the OCR by copying and pasting some of the text into a text file.

Happily I can report that the majority of the files that we receive pass quality inspection; however, occasionally rework is required. Some of the reasons that the bag might be rejected include: missing pages without a target, images being out of focus, images that are over or under cropped, incorrect page orientation, pages being skewed, and images being too light or too dark.

Once a bag is approved in Sampler the master files are copied to long-term tape storage and the derivative files are eventually published on the public website where users can access them. The contractor is notified if a bag is rejected and why and is expected to supply corrected rework, which will once again be reviewed when it is resubmitted.

After the bag has been accepted or rejected, we update our own in-house database record to note if the bag was accepted or rejected. The bag ID is copied and used to open the correct record in the database and each person marks their name as the reviewer. The bag is once again marked as accepted or rejected within this database, along with the reason for rejection if applicable.

Not all of our work is publicly available; some items may be restricted due to Copyright and are only available while on-site at the Library of Congress. Examples of our publicly available reformatting work can be found on the Library’s website.

Here’s a sample of some of the work that has been quality reviewed by RPS for Brittle Books:

• Union signal and world’s white ribbon …
• Dixie wood-worker.
• Mythology and early Greek history;
• How to make things go (the strenuous career)

Stay tuned to more posts from the Preservation Services Division and the Reformatting Projects Section that contain further discussion about our work!