Split from http://endlessparadigm.com/forum/showthr...#pid337954

(28/11/2010 06:27 AM)ZiNgA BuRgA Wrote:  ^ Image downscaled to 720x405, then upscaled back to 1280x720 (Lanczos) + sharpen filter:


Hardly looks 720p worthy.

If they're using someone else's raw, that makes sense then.

Damn lanczos creates way too much haloing.  Meh, that's expected, from a sharp resizer.  Bilinear on the downsize if you plan on bring it up again without too much haloing, but then again, it'll be blurrier, so tradeoff.

But about it not looking HD quality, it's just the lack of details, I doubt that has too much to do with the raw being bad.

(This post was last modified: 29/11/2010 09:23 PM by ZiNgA BuRgA.)

(29/11/2010 03:58 AM)Assassinator Wrote:  Damn your sharpener creates way too much haloing.

I suspect that would probably be the JPEG artefacts it's sharpening.

(29/11/2010 03:58 AM)Assassinator Wrote:  But about it not looking HD quality, it's just the lack of details, I doubt that has too much to do with the raw being bad.

Probably so, but lack of detail is enough reason not to make it HD.

(29/11/2010 04:02 AM)ZiNgA BuRgA Wrote:  

(29/11/2010 03:58 AM)Assassinator Wrote:  Damn your sharpener creates way too much haloing.

I suspect that would probably be the JPEG artefacts it's sharpening.

Nah, it's just the downsize that creates most of the haloing, not the sharpening.  I realized and edited the above post afterwards.

And jpeg artefacts?  You used PNG lol.

(29/11/2010 04:02 AM)ZiNgA BuRgA Wrote:  Probably so, but lack of detail is enough reason not to make it HD.

Yes, ofcourse.

(This post was last modified: 29/11/2010 04:22 AM by Assassinator.)

(29/11/2010 04:14 AM)Assassinator Wrote:  And jpeg artefacts?  You used PNG lol.

Source was JPEG, so everything I work off has artefacts.

(29/11/2010 04:39 AM)ZiNgA BuRgA Wrote:  

(29/11/2010 04:14 AM)Assassinator Wrote:  And jpeg artefacts?  You used PNG lol.

Source was JPEG, so everything I work off has artefacts.

The original picture you posted looks fine.  Don't see any major artefacts.

Errr... you mean, source is h.264?  (Which I guess is closer to JPG than PNG, since they're both DCT and all, but still different).

No, JPEG artefacts quite a bit, even if you don't notice them much.  Downscaling increases the "significance" of artefacts, upscaling it enlarges them, then sharpening pronounces them more.

Sorry for getting off topic.

(29/11/2010 05:11 AM)Assassinator Wrote:  The original picture you posted looks fine.  Don't see any major artefacts.

I saved it as a JPEG and I know MPC doesn't use max quality, it does generate some artefacts.

Only posted it to give a general idea on the picture quality, didn't expect it to be tested xD

(This post was last modified: 29/11/2010 06:33 AM by S7*.)

(29/11/2010 06:32 AM)S7* Wrote:  I saved it as a JPEG and I know MPC doesn't use max quality, it does generate some artefacts.

Only posted it to give a general idea on the picture quality, didn't expect it to be tested xD

Yeah, MPC's JPEG is pretty crappy I remember.

Maybe because that picture doesn't have many sharp details, and is of a bright color.

(29/11/2010 05:21 AM)ZiNgA BuRgA Wrote:  Downscaling increases the "significance" of artefacts

For large problems maybe, but for small almost unnoticeable problems, downscaling would just blur that to oblivion.

Downscaling simplified is just like taking the average, and it's this process of taking the average itself which is what creates the artefacts.  The fact that there is some small (note the small) amount of artefacts from the start should have an even smaller impact on the average.

EDIT: Plus, JPG doesn't cause haloing, so the problems don't match anyway.

(This post was last modified: 29/11/2010 07:35 AM by Assassinator.)

(29/11/2010 06:56 AM)Assassinator Wrote:  Downscaling simplified is just like taking the average

Hardly.  Perhaps only the case with something like a bilinear scale.  Certainly not the case with lanczos.

(29/11/2010 06:56 AM)Assassinator Wrote:  EDIT: Plus, JPG doesn't cause haloing, so the problems don't match anyway.

It doesn't, but the combination of everything can result in it.

(29/11/2010 04:47 PM)ZiNgA BuRgA Wrote:  

(29/11/2010 06:56 AM)Assassinator Wrote:  Downscaling simplified is just like taking the average

Hardly.  Perhaps only the case with something like a bilinear scale.  Certainly not the case with lanczos.

Ok, maybe "average" is the wrong word for that.  What I mean is whatever method, you're doing some type of interpolation, which is akin to fitting some sort of curve or system of curves through a set of points.

In the extreme case, with a dumb nearest neighbor method, you're just dropping an evenly spread percentage of all points (eg. ever second point for a 2x downsize).  That method produces the sharpest output, and the resulting data still contain exactly the same percentage of artefacting relative to the original, since the point dropping method does not discriminate between "good" or "bad" points.

Any other interpolator, which produces a curve smoother than a staircase (ie. everything else), should be less effected by "special" points than the nearest neighbor method, thus the artefacting would get "smoothed away" to some degree compared to the original.

(29/11/2010 04:47 PM)ZiNgA BuRgA Wrote:  

(29/11/2010 06:56 AM)Assassinator Wrote:  EDIT: Plus, JPG doesn't cause haloing, so the problems don't match anyway.

It doesn't, but the combination of everything can result in it.

Even if it does, the part that it played should be so small it pretty much wouldn't matter.  Sharp downsizing always results in haloing, comes with the territory, however lossless the source.

(This post was last modified: 29/11/2010 07:12 PM by Assassinator.)