Images are visual resources for users to look at. It is best practice for image files to be published in a quality for a user to tell what the image is about. Image quality is also expected to reflect the changes in technologies over the last years: displays’ screen resolutions have increased significantly since then. Correspondingly, user expectations have changed too, which requires image quality to be significantly higher than in 2008 when Europeana started.
If you are contributing image material because you want it to be discoverable in the Europeana website, then you need to provide at least a link to the image file or a website on which the image file can be accessed. You must also provide a direct link to an image file of at least 0.1 megapixel in size to have the means to create ~400 pixel-wide preview images to illustrate search results in the Europeana website.
*Thumbnail is available: true only if the "edm:EuropeanaAggregation/edm:preview" is filled and the associated edm:WebResource exists with technical metadata (ie. ebucore:hasMimetype filled)
**An image is available with resolution >= 0.1mp: true if one of the edm:WebResource associated via edm:isShownBy or edm:hasView exists AND technical metadata (ie. ebucore:hasMimetype filled) is extracted from that media resource