Added some subpixel frames as inbetweens to your original animation:
Its a little rough but with some more time I'm sure it could work
Take a cookie!
I'm just thinking it will take forever to sub pixel all the animations at least until I get better at it so it would be nice if I could separate the steps without creating lots of extra work.
Doing it in passes might also help with the skill gulf pistachio raised recently (I like that name for it ).
The process sounds right. Subpixels can be added as third step to smoothen the whole animation even more out.
You even want to have polished frames to add them, to exactly interpolate the medium steps. If it's a circle animation you just add between all frames a subpixel frame (if you have a 5 frame loop you will then have a 10 frame loop with subpixels, if you have an 8 frame loop you will have an 16 frame loop with subpixels)
An interesting thing to mention is that those kind of animations just work, if the speed between the frames is high enough, that you rather see the flow of the pixels and not the individual pixels of the frames (so it is mandatory that you don't move below twos / 80ms/frame.
The faster the movement and the better the interpolation the smoother it will look.
Another thing is that for outlined sprites you don't want to destroy the outline color with your subpixels, so rather use 2 very close colors if you need to suggest subtle movement there
Another thing is that subpixel movement tends just to work great for idling or other really subtle movements.
It works just to an certain extend for really fast movements which aren't a nearly linearly timed circle, since those animation usually have different distances distances between the frames.
For really fast animations like swordswings etc. you usually just smoothen the slow in and slow out and don't add any new frames or inbetweens in the main part of the animation to keep the snappiness.
So if you want to add subpixelling to a swordstrike, which is made out of 5 frames ( 1entry 2rewind 3tension 4atk swoosh 5 stop frame) you would modify it to something like 1 s1 2 s2 3 4 5 s5 but you won't add an inbetween everywhere, because otherwise it will look to smooth and it will loose a lot of power.