Versions Compared

Old Version 2

changes.mady.by.user Andrew Woods

Saved on

compared with

New Version Current

changes.mady.by.user Goines, Chip

Saved on

Key

  • This line was added.
  • This line was removed.
  • Formatting was changed.
Comment: added blurry pdf issue

...

  • When users experience slow loading or broken images in HOLLIS, HOLLIS Images, Harvard Digital Collections, 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summary, occasional slow loads or error messages like the above may be experienced until the migration is finished and outdated images are addressed.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.