Cover Image Cache
From Open Media Collectors Database
1. Item Cache
Every URL that is saved to an item attribute whose s_attribute_type file_attribute_ind = 'Y' will be cached locally by the item cache functionality. In addition a thumbnail will be generated for all supported Image urls. (GIF, JPG, PNG)
The benefit of the new functionality introduced in 1.X is that the item attribute URL is not destroyed upon saving a local copy. Its also possible to periodically refresh the cached images / thumbnails.
2. File Uploads
Beginning with 1.5 file upload functionality has been refined to be separate from the item cache. Thumbnails of uploaded images are stored in the item cache, but the uploaded images are stored in the upload/ directory. A limitation of the implementation means that the uploaded file name must be unique or else it will be treated as a reference to the original image. The upload functionality will automatically generate unique filenames where clashes occur. This resolves an outstanding clone items issue where uploaded images could not be cloned, now they will automatically be cloned because the image reference is globally unique.
For additional discussion on the 1.x implementation of item cache and revised upload functionality in 1.5 check out the forum post.