Dead links for images or image sizes

[hinzed1127]

Lots of image thumbnails don't seem to be available in the 3 sizes listed by the README:

Image thumbnails are accessible by their object id in three sizes: http://api.artsmia.org/images/$id/{small,medium,large}.jpg. Small images are 100px on the long side, medium images 600px and large images 800px.

For example: http://api.artsmia.org/images/29486/small.jpg works just fine, but replacing "small" with "medium" or "large" does not.

However, looking into the collections website source, I found this function that seems to generate 3 sizes consistently, though the endpoint is a little different:

`https://${id%7}.api.artsmia.org/${size}${id}.jpg`

Is this an acceptable and stable alternative, and should the README be updated to reflect this?

Update : The second option appears to also sometimes yield 403 errors. I'm using image IDs from the random artworks endpoint and filtering for image:valid and restricted:0. Are there other parameters I should be matching to ensure an image is accessible?

[kjell]

Hi! Yes - the {s}.api.artsmia.org/{size}/{id}.jpg URL is valid and usable - we've added a CDN to serve up image files faster than the live endpoint on our API server. Adding that to the documentation is a good idea.

The s (subdomain) param is to streamline loading multiple images on one page - most browsers only load one resource at a time per domain, so spreading images across multiple subdomains allows a performance boost.

On the CDN, size should be either 400 or 800 instead of {small, medium, large}.

Theoretically the CDN is updated daily with all the newest images, but I suspect the 403 errors reflect intermittent failures in those updates. We usually deal with these case-by-case as they are pointed out to us but I'll look into if there's a way to do so more systematically. I looked through the random search results that should have a valid image and be unrestricted and eventually found a 403 at https://1.api.artsmia.org/400/65270.jpg - I'll look into why