[HN Gopher] Exploiting Aliasing for Manga Restoration ___________________________________________________________________ Exploiting Aliasing for Manga Restoration Author : lnyan Score : 61 points Date : 2021-05-06 10:58 UTC (1 days ago) (HTM) web link (github.com) (TXT) w3m dump (github.com) | polishdude20 wrote: | Wondering how this compares to just a sharpening filter? | Isamu wrote: | Cool approach, and I am glad to find out there's a manga dataset | out there for academic use! | | http://www.manga109.org/en/ | flakiness wrote: | Yeah, I hope it were available without contacting them, but | it's probably too much to ask. | chocolatkey wrote: | As someone who gained access to this dataset, I will say that | the image resolution is disappointing. Maybe that's what | inspired this paper | cleansingfire wrote: | While the aliased sample is sharper, I experience an unpleasant | artifact in that version based on the halftone dots lining up | with pixels, with an effect like grid illusion. | https://en.wikipedia.org/wiki/Grid_illusion?wprov=sfti1The blurry | character of the original is also unpleasant, but the aliased | version is hard for me to look at. I'm interested to know if | anyone else experiences this. | lupire wrote: | It's not even an illusion; it looks bad because they have a | terrible tile for the dithering. Should be easy to fix in a | postprocessing step after the AI. | xwdv wrote: | I agree, it was hard for me to tell exactly what was the | restored version as both images had unpleasant flaws. | Groxx wrote: | I kinda wonder how this would compare to an upscale and sharpen - | a good amount of these screentone patterns are solid blacks on a | consistent white or gray, which seems like it should work fairly | well. Or maybe that'd round too much off - this is doing a pretty | good job of keeping line-quality intact. | | That said, this is an interesting technique, and looks pretty | good in the end... but the minor misalignments / pattern-jitter | in some areas would probably bug me more than the blurry image, | tbh. Seems like that could be improved somehow though, maybe by | modifying the pattern it decides on with something similar but | not original-pixel-aligned? | | --- | | edit: after writing the above and looking back at it a third or | fourth time: I've changed my mind, the patterns this is producing | will very likely look better than a sharpen when they're closer | together or more heavily aliased. They're "plausible" and still | look like patterns, sharpens have some terrible edge cases on | stuff like the remote(?)'s frame. Maybe they just need some more | examples / side-by-sides? I imagine more will be in the final | paper, whenever that's linked. | crazygringo wrote: | This is really clever! | | I love whenever it's possible to upsample/restore media due to | known constraints in the original -- in this case, how screens | work. | | Something analagous I've been waiting for is regenerating old | scratchy piano recordings. Piano is unexpectedly simple compared | to other instruments -- the only inputs are really note down + | speed, note up, sustain pedal pressure, and (less frequently) | soft pedal pressure. | | Seems like you should be able to turn any solo piano recording, | no matter how degraded, into a relatively lossless MIDI | representation, then re-record that replayed physically (via | motors, which exist already) on a modern piano, or even just | synthesized, trying to be as true to the original piano's | characteristics as possible. Losing literally none of the | artistry. | | It seems like this should be "easy" for piano in a way that it | isn't, for example, with violin which has so many more | complicated characteristics of pitch, timbre, bowing, vibrato, | etc. | cclark00 wrote: | This has been done in various forms! One interesting one is | shown in https://www.youtube.com/watch?v=6hv2zh_Z0Io Sergei | Rachmaninoff recorded a 78 album simultaneously with a piano | roll of several pieces - thus capturing the 'keystrokes' and | the audio of intonation of the master's hand. The piano roll | was converted to an automatic reproducing piano (super high end | player piano, a Bosendorfer 290SE) and massaged by an expert to | sound almost exactly like the 78. Then it was re-recorded in | modern fidelity, playing back from the 290SE. It is exciting to | see and hear a 290SE (re)play in person, but a little weird in | a concert setting with no pianist to watch. | crazygringo wrote: | That's amazing, thanks! I was even thinking that | Rachmaninoff's recordings would be where I'd start. | | It's like a ghost playing. Absolutely crazy to hear _his_ | touch but with modern fidelity. | zitterbewegung wrote: | A piano can be intentionally and or unintentionally not in | tune. Every Piano has its own unique sound (due to manufacturer | and also form factor) and is played in a place where | temperature can have another affect in the sound. | | But it looks like already people have attempted the | transcription strategy you describe | https://www.google.com/search?hl=en&q=machine%20learning%20n... | cevn wrote: | When you translate to MIDI, you are going to lose a lot of the | subtle pitch and tonality of the piano. One string vibrating | produces overtones and a chord will vibrate in a very deep way | on a grand piano that I feel you cannot replicate in a MIDI, | and therefore that detail would be subsequently lost. | | For instance, how long you are touching the string - while | you're touching the string, there is a sound - but after you | let off, you get the "reverb" - and there is different reverb | for how you hit the key, if you bounce, or if you stay for a | split second longer for staccato, I don't feel like these | subtleties translate to MIDI. | | It is certainly easier than violin, that I will grant. | | edit: IMO the best way to do what you are describing is get a | really good pianist to sit down and do the work. I don't think | that (current?) machine learning can really "understand" the | nuance of phrasing esp that would be coming from older | recordings. | crazygringo wrote: | > _I don 't feel like these subtleties translate to MIDI_ | | But wouldn't they be reproduced when replaying the MIDI data | physically on a piano? | | Ultimately isn't how you hit the key and bounce/stay still | just initial velocity and then timing of letting go? Perhaps | the velocity of letting go would have to be added as well, | but I'm not actually sure if that's really acoustically | meaningful. | | I guess I don't see why all the reverb and ultimate sound | complexity wouldn't be recreated in playback? Of course, this | requires actual physical playback on a similar enough model | of piano, or else a synthesizer that is sufficiently | accurate. | cevn wrote: | Well - for one thing there is the pedal is not itself | binary but in degrees - and there are three pedals, one of | which if you depress, will silence only some of the | strings. I don't think MIDI itself is capable I guess, some | other format might be. There are a lot of factors, and | pianos sound different from each other, I think that would | be lost. | crazygringo wrote: | MIDI is definitely capable -- code 64 is used for sustain | pedal, and code 67 for soft pedal. And it's associated | with a byte value for how far the pedal is depressed. | | The third (middle) pedal in pianos is nonstandard -- i.e. | used for different effects on different pianos, whether | sostenuto or bass damper or practice mute. | | In actual performance the only time it's ever really used | (and rarely at that) is as sostenuto, since that's what | it does on grand pianos like Steinways, but its effect is | indistinguishable from simply holding notes for longer | durations, so MIDI can simply represent its effect that | way. (Unlike the sustain pedal which increases resonances | in a big way and needs to be represented independently, | or soft pedal which changes timbre as well as volume.) ___________________________________________________________________ (page generated 2021-05-07 23:00 UTC)