[NoWai]

Over the last month, i've been thinking about when such types of encodes are justified(if at all) and what are the best choices one can make when encoding them. Seeing that Mentar has done his share of the research, i'd like to ask a few questions myself.

How can one easily tell apart from a source which was originally HD and then downscaled and upscaled by some broadcaster? How can we tell if they didn't take a very clean SD source, upscaled it then warpsharped(or some other line thinning filtering)? I have one such source where it lacks the background detail, and it's known it doesn't air in HD, yet there we see nice thin lines and contrasts. I'm unable to tell whether this was originally an SD source which was upscaled and sharpened or if it was a HD source which was downscaled then upscaled and sharpened. As for seeing if a source is genuine HD we can easily downscale/upscale then subtract() from original(avisynth) and we'll see clear thing lines as well as detailed backgrounds showing up in the subtracted result.
If you apply the same procedure to some better upscales like Mentar's MHD ShanaS02E01 and a few other ones, you can see that the lines have been enhanced and thus downscaling/upscaling loses some of that detail. (even if its made up detail!)

Originally Posted by Mentar

The _best_ (subjective!) results were reached with a combination of supersampling to 1.5x source resolution, sharpening, mild linedarkening, mild antialiasing, downsizing, and finally (key) slight _linethinning_ (originally, only to warp away sharpening halos a bit). Initially, I couldn't understand that, really. Why did linethinning have such an impact on the visual impression?

Just want to clarify a few things in that paragraph which aren't clear to me.
Source resolution? SD (704x396 for example?), WS or some other SD res.
What kind of sharpening was applied? limitedsharpenfaster, msharpen..
line darkening? msharpen or fastlinedarken or others?
Downsize? back to what resolution original? (then we'd have SD resolution in which case i don't fully understand what was the purpose of this?)
Linethinning? What filters are recommended for this? I've played a bit with some variations of warsharp, but i can't settle on using them as i notice how radically they change the image, even if i use only a bit of them, they don't just change the lines, they change the whole image.

Originally Posted by Mentar

So I began looking for sources which had "finer" structures. And there they were - 1280x720 captures of HD-mastered material. Here, filtering could be done quite differently: Just to clean up the lines, doing some very mild line removal and sometimes line mending (mild antialiasing). So the background details were multi-pixel blobs and not really sharp? SO WHAT. That's not where the eye was looking.

What filtering do you mean by line removal?
What antialiasing is prefered? Doesn't antialiasing itself upscale the image once, filter it then downscale?

Originally Posted by Mentar

So, to wrap it up, we need to agree to disagree. Type 2 cases _absolutely_ deserve a HD resolution release in my opinion. Here, going SD is in fact generally harmful, because the lines tend to be thinned too much, leaving a strange look of unstructured color plains. Whether you call them HD (I do and consider it justified), MHD (we can tag them "Middle HD" instead of the Mentar pun) - I don't care. They're an important and fairly large class of sources which deserve proper handling.

I've come upon a source which was captured in HD 720p but it's clearly upscaled from SD resolution. I'm not entirely sure if the original was mastered in HD, even if we have clear detail and clear thin lines in the HD upscale, however i know that by downscaling and slightly msharpen'ing(with some AA) i am losing some detail as compared to the original HD capture.

So my questions sum up to this in the end:
What are recommended ways of downscaling if we chose to go that way instead of leaving it in HD? When do we know we should leave it in the captured resolution and what filtering(both general ideas and specific recommended filters) is recommended for enhancing the lines in such captures.


These questions have been bothering me for the past month and i hope i didn't ask a bit too much.