By that I mean, I know what bilinear/bicubic/lanczos resizing algorithms are, and I know they should at least have acceptable results (compared to NN).
But I don't know famous libraries (especially OpenCV which is a computer vision library!) could have such poor results.
Also a side note, IIRC bilinear and bicubic have constants in the equation. So technically when you're comparing different implementations you need to make sure this input (parameters) is the same. But this shouldn't excuse the extreme poor results in some.
At least bilinear and bicubic have a widely agreed upon specific definition. The poor results are the result of that definition. They work reasonably for upscaling, but downscaling more than a trivial amount causes them to weigh a few input pixels highly and outright ignore most of the rest.
I've seen more than one team find that reimplementing an OpenCV capability that they use gain them both in quality and performance.
This isn't necessarily a criticism of OpenCV, often the OpenCV implementation is, of necessity, quite general, and a specific use-case can engage optimizations not available in the general case
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I'm shocked. I don't even know this is a thing.
By that I mean, I know what bilinear/bicubic/lanczos resizing algorithms are, and I know they should at least have acceptable results (compared to NN).
But I don't know famous libraries (especially OpenCV which is a computer vision library!) could have such poor results.
Also a side note, IIRC bilinear and bicubic have constants in the equation. So technically when you're comparing different implementations you need to make sure this input (parameters) is the same. But this shouldn't excuse the extreme poor results in some.
At least bilinear and bicubic have a widely agreed upon specific definition. The poor results are the result of that definition. They work reasonably for upscaling, but downscaling more than a trivial amount causes them to weigh a few input pixels highly and outright ignore most of the rest.
Not so fast: https://entropymine.com/imageworsener/bicubic/
Fair. To be clear the issue remains no matter the choice of these parameters.
I've seen more than one team find that reimplementing an OpenCV capability that they use gain them both in quality and performance.
This isn't necessarily a criticism of OpenCV, often the OpenCV implementation is, of necessity, quite general, and a specific use-case can engage optimizations not available in the general case