Check IIIF Image Dimensions Before Choosing a Photo Download
By ImgHeal · Updated
A IIIF image information response can describe the service's dimensions and capabilities. Use it to choose an appropriate permitted download, then verify the saved file. A deeply zoomable viewer does not by itself establish that a particular download contains the same number of source pixels.
Explore this topic: Find original photo files
Locate the correct image service
Begin with the repository's supported IIIF reference and identify the image service for the exact view you need. Multi-view objects may have separate services for front, back, and detail captures. Record the object ID and view label before inspecting image information. Avoid treating a service from a thumbnail or unrelated canvas as the full source. If the institution supplies a direct download with clear dimensions, compare that route as well rather than assuming a manually constructed request is always better.
Review dimensions and supported requests
The IIIF Image API defines an information resource, commonly ending in info.json, with technical properties and advertised capabilities. Inspect the version and relevant limits before requesting an output size. Keep the requested dimensions within the service's documented behavior and permissions. Do not infer that a large numeric request creates captured detail beyond the underlying image. If the service rejects a request, use its supported options or contact the institution rather than repeatedly increasing parameters or attempting to evade restrictions.
Inspect the saved derivative independently
Open the downloaded image in a trusted viewer and check its actual pixel dimensions, orientation, and visible border. Compare a fine detail with the institutional viewer at a meaningful scale. Record the request, source reference, and filename so the same derivative can be understood later. Keep an untouched downloaded copy before preparing an ImgHeal upload or another edit. A successful high-pixel-count download improves the starting material only when those pixels contain useful source information; it does not validate generated facial texture, unreadable text, or inferred original colors.
Check this workflow
- Match the service to the exact object view.
- Read supported dimensions and limits.
- Verify the downloaded file's actual pixels.
Sources and further reading
- IIIF: Image API 3Defines image-service requests, information responses, supported transformations, and limits.
Questions about this restoration task
Does a larger IIIF request always contain more original detail?
No. Check the underlying image information and actual output. Resizing a derivative cannot guarantee additional captured information.
Continue with a related guide
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