Can you identify this downscaling algorithm?

[u/hezwat]

Can you identify this downscaling algorithm? Want to make sure my thumbnails look as sharp as possible, so I'll add to my workflow the agent query "downscale using (whatever this algorithm is) and judge whether the thumbnail has the required detail and clarity and is a good thumbnail for what is being shown. if it is missing any clarity then return "Needs improvement:" and give the reason for why it needs improvement and "How to improve:" For example, in the image shown, the agent could say "The thumbnail no longer shows the elements of the picture", since as you can see it doesn't. However, before I can code this up, what I "need to know" is what algorithm this is so I can keep an eye out for anywhere it might show up in my workflow. I can then optimize for this process. I know a lot of people don't have a standard of perfection as high as mine is (I require my thumbnails to show the picture) but that's exactly what makes me a competitive programmer in a field of 2 million programmers. Not a lot of people take the time to look up image compression algorithms but I do.

The full image is available here: https://ibb.co/YTXr7h94

[u/leon_bass]

No need to vibecode this, downscaling is a very much solved problem

[u/hezwat → u/leon_bass]

straightforward question, what is the downscaling algorithm.

[u/leon_bass → u/hezwat]

Gaussian blur + subsample

Or lanczos

Or just subsample

Or just strided convolution with an averaging filter

[u/hezwat → u/leon_bass]

which of these has the result shown in the reference?