Sadly it is not 'jpeg-and-png' and you do need to keep some images in PNG becuase you cannot have transparency in JPEG.
Much can be done with 4:2:0 colour and the optimiser tools Google recommend. In PNG world I like pngquant for some images but not all. It is also possible to prepare images in Imagemagick to suit an optimiser.
However, storage is cheap and there are better ways. Google's Pagespeed for NGINX and Apache works wonders at serving optimised images. This abstracts the problem away from code so there is no need to be worrying about image sizes over the web, size in pixels or bytes.
I don't think this tool is about providing a professional archiving solution, just efficiently processing an online image library so that you have an extremely practical archive regardless of what compression ratio images were originally uploaded at.
The use of all cores to quickly process all images was instructive. However, in real life it is more useful to have a cron job that just updates all images to correct standards slowly in the background, not using all cores.
I would like to see some comparisons against more commonly used jpeg optimisers.
1. Convert to png
2. Save image on multiple storage mediums
1. Re-encode lossily.
Flickr only allow you to buy an account for the next 2 years.
With hardware costs going lower and lower, and rate limits enforceable to keep this for archivig, you could model a price with a suitable profit margin.
Why not buy instead one or even multiple cheap but large USB hard disc and put it into your shelve or to your friends? It gives you immediate access for free. I don't get it why one rents a service instead of staying independent.
Copies that can't be read aren't copies any more, which means regular access is a requirement, which means another recurring expense.
Different requirements can reasonably result in different solutions, but a USB hard drive on its own is simply not comparable to storage service. A redundant set of USB hard drives with a specified replacement schedule and testing procedure would be comparable -- but if you amortize all that out, we're talking about $X + Y hours per month for Z GB of storage, which compares directly to $X/GB-month if time has a dollar value.
From this perspective, I argue that storage services like S3, Glacier, B2, and Digital Ocean Spaces are priced fairly.