samvera
Incorrect tile size in manifest
Discussed in https://github.com/samvera/serverless-iiif/discussions/174
Originally posted by cweinard April 24, 2025 Hello, We're serving pyramidal tiffs with tiles at 256, and the function parameters all seem to be set at 256, and yet the info.json manifest is showing tile dimensions at 512. Is there a way to correct that? (Or is it even something to be concerned about?) Thanks!
Do you think this could be related to that issue we were seeing before, when some of the tiles were offset?
No, this is a bug going way back to the very earliest days of serverless-iiif. It should have been fixed long ago.
I mean in the sense that if the info.json are listing tiles are double the size would that be exacerbating the issue with the offset because OSD is requesting larger tiles?
Ah. No, I don't believe so. That had to do entirely with the page selection and trying to extract adjacent tiles from different resolutions. This just affects the efficiency of tile extraction – if the requested tile is of a size or on a boundary that doesn't match the precomputed tile size, the image processor will have to do more work to perform the extraction.
This issue is proving to be trickier than I thought. The solution might end up being some combination of global defaults and a per-file override (in metadata) to tell the system what tile size to report. On-the-fly extraction of metadata is too unreliable and slow to be a practical solution, especially since the serverless nature of the system prevents caching the source file locally the way a stateful IIIF server would.