[popcornmix]

@popcornmix

Is something like lanczos/spline/catmull-rom possible or are they completely different algorithms?

No, should be possible with right coefficients. This is lanczos with A=2.

Code:

vcgencmd scaling_kernel   0  -2  -7 -14 -19 -23 -20  -9  12  41  79 123 167 207 237 253 253 237 207 167 123  79  41  12  -9 -20 -23 -19 -14  -7  -2   0