Image Delivery Service Known Issues

Slow or degraded image performance

• When users experience slow loading or broken images in HOLLIS, HOLLIS Images, or CURIOSity, there are a few factors that may be contributing to the issue.

  1. Some of the image delivery technologies used by the Libraries have degraded in their ability to reliably serve images.
  2. Many older images in our collections have invalid metadata that are incompatible with newer generations of imaging standards and software.
  
  

  To address these problems, the Library Technology Services has several projects underway:

  • We have rebuilt and updated our image delivery systems to support the latest versions of IIIF and use a modern, well-maintained image server.  In order to take advantage of the new systems, we are in the process of migrating over 42 million images to the new environment. This migration is expected to be complete in the first quarter of next year.
  
  
  • We are upgrading our image viewer software from Mirador 2 to the newer Mirador 3. A beta of Mirador 3 is available now but the full transition depends on the image migration.
  
  
  • A project is identifying images with invalid or incompatible metadata so they can be remediated or regenerated to load properly.
  
  

  We have recently made a change that displays a placeholder image instead of images that we have determined to have invalid header data and may not load correctly.  The placeholder image looks like this:

In summary, occasional slow loads or error messages like the above may be experienced until the migration is finished and outdated images are addressed. Library Technology Services is working actively to complete these upgrades and resolve issues to improve the digital experience.

Blurry PDF pages due to small image sizes

• • when a pdf comes out as blurry, it is most likely due to the fact that the full image size is less than the 1200 x 1200 iiif image api call. this results in blocky text, as the pixels are blown up 2X or more to fit the screen.
  • redepositing the jp2 so that the full image is larger than 1200 x 1200 px when rendered into a jpeg will fix the issue, if redepositing a larger size jp2 is possible.

Restricted images not displaying in embedded Harvard Viewer

There is a known bug in the Harvard Viewer display of "restricted to Harvard" images when viewed in HOLLIS, HOLLIS Images or CURIOSity. If you are not already logged in to HarvardKey, the Viewer should prompt you to log in. Instead, the frame is empty or you get a message "www.pin.harvard.edu refused to connect". The solution (for the Harvard community) is to click the "Log in" link near top-right of the page. Or click the "Open image in new tab" link above the Viewer to open the image in a separate tab and you will be prompted to log in. If you are an independent researcher not affiliated with Harvard, none of these work-arounds will help. In this case, you have 2 options -- visit a Harvard library in-person and within the walls of that library you will be able to access restricted digital materials. Or you can contact the owning library in case they can help you.