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lepton
Discontinued Lepton is a tool and file format for losslessly compressing JPEGs by an average of 22%. (by dropbox)
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InfluxDB
Power Real-Time Data Analytics at Scale. Get real-time insights from all types of time series data with InfluxDB. Ingest, query, and analyze billions of data points in real-time with unbounded cardinality.
It may not be directly related to your question, but Dropbox has developed a great open source software called Lepton. It is able to compress JPEGs losslessly and saves on average about 22% of storage space. The files are not readable after compression without decompression, but since your focus seems to be on archiving anyway, it might be handy. And for larger collections of high-resolution images, it can actually save a decent amount of storage space.