Upscaling small images

[tong]

A image upscaling tool (like Upscayl) could be used to increase the resolution of small program photos.

Here are some examples: https://github.com/verein-fuer-elektro-akustik/velak.klingt.org/commit/de905ce0fe34e69746ed0272365259411b682899?short_path=f0d60d5#diff-f0d60d5319875889d2d6b68c0cc5a8699a123b8536db681ec9f10fc861a2b82f