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The Image Delivery Service (IDS) delivers still images stored in the Harvard Library Digital Repository Service (DRS) to a web browser. Images available through this service come from archives, museums, libraries and other collections throughout Harvard University. IDS can deliver images statically (just the image) or dynamically (image in a viewer) and will secure images to the Harvard community (i.e., to those with a Harvard Key) when the appropriate access flag is set in image metadata.

Supported still image formats

IDS will deliver all DRS-supported still image formats (TIFF, JPEG2000, JPEG, and GIF) as a web-accessible JPEG file.

Linking to a static image

A static IDS url will deliver an image to the browser without additional features or menus. A static url without additional parameters will resolve to a medium-sized JPEG. Note that by policy, the maximum image delivery size supported by IDS is 2400 pixels in the longest dimension.

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Note: All still images deposited to DRS with role=delivery are automatically assigned a delivery URN that points to an IDS static url. It is recommended that you use the IDS urn to refer to still images in catalog records and web sites.

For example, a static view of still image #1639647 can be delivered using an IDS url or preferably, a persistent IDS urn. The following image links:

https://ids.lib.harvard.edu/ids/view/1639647    
https://nrs.lib.harvard.edu/urn-3:fhcl.hough:408019 

will deliver a static image to the browser:

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Linking to a dynamic image in the HL Viewer

A dynamic IDS url will open an image in the web-based Harvard Library (HL) Viewer, which lets the user zoom, pan and rotate the image as well as share the link or download the image file.

To create a dynamic IDS url, append the buttons=y parameter to a static IDS url or IDS urn, e.g.:

https://ids.lib.harvard.edu/ids/view/1639647?buttons=y     
https://nrs.lib.harvard.edu/urn-3:fhcl.hough:408019?buttons=y   

Below is a screenshot of still image #1639647 displaying in the HL Viewer:

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Notice that the dynamic IDS url resolves to a different url format:
https://iiif.lib.harvard.edu/manifests/view/ids:1639647 

The “iiif.lib.harvard.edu” url is the address of the backend iiif server that provides the HL Viewer user interface. While this address can be bookmarked and is reasonably persistent, it is recommended that permanent links to a dynamic image in a catalog record or web site use the IDS urn, e.g.:

https://nrs.lib.harvard.edu/urn-3:fhcl.hough:408019?buttons=y will resolve to https://iiif.lib.harvard.edu/manifests/view/ids:1639647 

Note that the “iiif.lib.harvard.edu” url format for a dynamic image does not accept IDS url parameters.

IIIF Image API Support

IDS also supports links that conform to the International Image Interoperability Framework (IIIF) Image API.

IIIF is a set of community supported APIs that allow any image viewing application that supports the standard to embed digital image content from any supporting institution in their applications. The HL Viewer for still images uses this API to display highly zoomable images from the DRS.

See Linking to images using the IIIF Image API for more information.

Captions for still images

DRS still image metadata supports creation of a caption -- a brief description that can be displayed with an image. A caption can be defined at deposit or later using Web Admin. See Image Captions for more information. To set image captions in Batch Builder see Adding captions in Batch Builder.

For still images, a caption will always display in the dynamic view (the HL Viewer), in the white bar above the image canvas.

Image Modified

By default, this caption will include the owning organization’s name (prefixed by “Harvard University”), a comma and the DRS file object owner supplied name of the image. Even if caption display is turned off in DRS metadata, this default caption will display in the HL Viewer. If custom caption text is defined in DRS metadata, IDS will use it instead of the default.

The IDS static view of an image does not support caption display.

Setting maximum delivery size

The default maximum size for images delivered by IDS is 2400 pixels in the largest dimension. But curators can set a lower maximum delivery size for their images on a file-by-file basis. See Image Delivery Size Restriction for more information. To set maximum delivery size in Batch Builder see Adding rights restrictions in Batch Builder.

IDS will respect a lower maximum delivery size when displaying or downloading an image.   

Frequently asked questions

Q1: Does the HL Viewer for still images support display of a descriptive (METS) label?
A: No, not at this time. For the first new IDS release, caption metadata displays in the white bar above the image canvas. In the HL Viewer for page-turned objects (PDS), a METS label displays in that position.

Q2: Does the HL Viewer for still images support a way to cite the resource?
A: No, not in the first release of new IDS. A Cite feature is planned for a future release.

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