The native resolution of Blu-Ray source is 1280x720 and was interpolated to 1920x1080 with Gaussian Kernel during BluRay mastering/authoring. The interpolation results in blurry image and tiny, scrappy aliasing attached to edges. Though Gaussian Interpolation did not introduce troublesome artifacts like ringing, it cannot conceal the fact that there is no native high frequency component under 1080p except the OP/ED credit. So we ripped the video with inversed interpolation, sharpness compensation (Contra-Sharpening, etc.) and slight debanding.
The encoded image in the comparision was upscaled to 1080p by non-ringing Lanczos4 algorithm, which is to emulate baseline playback environment of our target viewer (General 1920x1080 digital monitor, MPC/Pot with madVR).
Resource Credit:
Thanks to dennis1011@U2 and jsum@U2
Stella-rium from 624322077@2dkf, BK from h_12439@U2
ここから、かなたから from ST30073
オリジナルサウンドトラック むつらぼしα from jsum
オリジナルサウンドトラック[YouTube Edition] from nyaa