What are some alternatives?
When comparing Search by Image Extension and DSpace, you can also consider the following products
TinEye - Reverse Image Search to help find an image's source, duplicates or altered versions.
VuFind - VuFind is a library resource portal designed and developed for libraries by libraries.
VisualData - Instagram for Visual Datasets
Invenio - Invenio is a free, open-source software to run a digital library or document repository on the web.
NooBox - NooBox is a Chrome Extension that provides useful functions, such as: Multi-engine Reverse image search, Extract Images, Screenshot & Search
Koha - Koha is the first free and open source software library automation package (ILS).