720p conversion to 1080i

[Guest]

Archived from groups: alt.tv.tech.hdtv (More info?)

> Frank Provasek wrote:
>
>> >> > If that were the only source of the problem, then everything
>> >> > would become crystal clear in stationary scenes.
>> >>
>> >> True, and that is very fatiguing to the eye, so a gaussian
>> >> blur
>> >> is applied to stationary scenes to match the motion blur...
>> >
>> > *cough* The motion blur depends on the SPEED of motion, so
>> > there
>> > is no such thing as a gaussian blur that "matches" it. Oh, and
>> > 24
>> > FPS film has a huge amount of motion blur just from the long
>> > frame
>> > exposure times, and I never noticed that fatiguing anyone's
>> > eye.
>>
>> Motion blur in video standards conversion refers to synthesized
>> frames to fill in where
>> frames are deleted or extra frames supplied. The algorithms
>> sometimes create a frame from
>> two frames 1/25 sec apart, giving an "exposure" of 1/12 sec.
>>
>> Normal 35mm motion picture film uses an exposure of 1/50 sec or
> faster.
>
> Have you ever looked at the individual frames in a fast moving
> film
> scene? The blur of one frame very commonly ends near where the
> blur of
> the next frame starts. That's actually the better way to do it,
> because using shorter exposures in fast moving scenes makes judder
> more
> noticeable. Shorter exposures, as have to be used in strongly lit
> scenes, highlight the inadequacies of 24 FPS frame rates pretty
> obviously sometimes.
>
> ...Which is not the main issue I called bullshit on: that there is
> no
> such thing as a gaussian blur that "matches" motion blur. The
> width of
> a motion blur, in pixels, depends entirely on how fast the objects
> in
> the picture are moving. The artificial blur applied to pal/ntsc
> conversion is INDEPENDENT of motion blur!
>
You have been wasting my time for a week that denying that
conversion looks bad
because of the frame rate problems, because "if that were the only
source of the problem, then everything would
become crystal clear in stationary scenes." Which if you look at a
raw output IT DOES, and since a picture that resharpens
and blurs when motion stops and starts is MORE annoying, a gaussian
blur is applied to the motionless
scenes to SUBJECTIVELY even out the "look." Then you argue about
THAT, but later say
" The artificial blur applied to pal/ntsc conversion is INDEPENDENT
of motion blur!"

Yes ..that is exactly what I said...it's an artificial GAUSSIAN blur
to SUBJECTIVELY match the
motion blur.

Definition of Gaussian Blur

http://www.maths.abdn.ac.uk/~igc/tch/mx4002/notes/node99.html

Then you argue that motion pictures blur more than video due to the
long exposure time. And claim
"the blur of one frame very commonly ends near where the blur of
the next frame starts"

IMPOSSIBLE (on a standard film camera) which typically uses a 170 or
180 degree shutter.
The film is blocked half the time so that the next frame can be
positioned. The long motion blurs you
describe are common (and physically possible) on electronic systems
ONLY, especially on material
produced with tube cameras, which have lag not applicable to film
EVER.

 

[Guest]

Archived from groups: alt.tv.tech.hdtv (More info?)

42 wrote:
> In article <1105935432.286827.94080@f14g2000cwb.googlegroups.com>,
> paul- NOZPAM@paulkienitz.net says...
>> Frank Provasek wrote:
>
>> ...Which is not the main issue I called bullshit on: that there is no
>> such thing as a gaussian blur that "matches" motion blur. The width
>> of a motion blur, in pixels, depends entirely on how fast the
>> objects in the picture are moving. The artificial blur applied to
>> pal/ntsc conversion is INDEPENDENT of motion blur!
>
> /shrug
>
> Eventually all TVs will be 1080p (or better), and capable of
> displaying both 1080i, and 720p (with simple resolution scaling)
> eliminating the need to 'convert' between them.
>
> Further, I -hope- eventually TVs will be able to accept, and display
> content at its source fps rate, so we won't be converting between 24,
> 50 or 60 fps rates. The broadcaster broadcasts at what rate it was
> recorded in, and the TV displays whats coming in at -that- rate.
>
> (I suppose to prevent there being a 'jar' in the aesthetics of the
> picture, commericals should be converted and encoded to match the same
> resolution and fps rate as the surrounding content...)

Hmm....my Mits converts my OTA FOX signal to 1080i. I guess it's better
than rejecting it all together......

That's what I get for buying too early. No 720p or 1080p support, no
DVI........of course, it is a good reason to upgrade!

 

[user]

Archived from groups: alt.tv.tech.hdtv (More info?)

In article <1106003154.562482.108600@z14g2000cwz.googlegroups.com>,
paul-NOZPAM@paulkienitz.net says...
> 42 wrote:
>
> > Eventually all TVs will be 1080p (or better), and capable of
> > displaying both 1080i, and 720p (with simple resolution scaling)
> > eliminating the need to 'convert' between them.
>
> Yes, the best way for a TV to be able to display both resolutions well
> is to be better than either. If it got up to 2160p every scaling issue
> would be completely gone. And since cinema projectors will probably go
> to 2160p in the near future, this isn't so unlikely a scenario...
>
> > Further, I -hope- eventually TVs will be able to accept, and display
> > content at its source fps rate, so we won't be converting between 24,
> > 50 or 60 fps rates. The broadcaster broadcasts at what rate it was
> > recorded in, and the TV displays whats coming in at -that- rate.
>
> And why not, computer monitors have been capable of variable frame
> rates for years and years. I would hope that in five years any old
> cheap TV could display PAL and other 50 FPS formats.

Yeah... except it could have happened 5 years -ago-... not sure why TVs
are lagging here. And until its widely adopted the broadcasters won't
support it.

> > (I suppose to prevent there being a 'jar' in the aesthetics of the
> > picture, commericals should be converted and encoded to match the
> > same resolution and fps rate as the surrounding content...)
>
> If the TV is based on liquid crystals or something similar, where the
> light output at any one pixel is continuous, the eye should not be able
> to detect a change of frame rate. If it's based on CRTs or DLP it
> might make a difference you could see.

Thus unless you see the near future extinction of CRT and DLP...

 

[user]

Archived from groups: alt.tv.tech.hdtv (More info?)

In article <G7idnVsT8NAUO3HcRVn-iw@comcast.com>, alpertl@xxcomcast.net
says...
> 42 wrote:
> > In article <1105935432.286827.94080@f14g2000cwb.googlegroups.com>,
> > paul- NOZPAM@paulkienitz.net says...
> >> Frank Provasek wrote:
> >
> >> ...Which is not the main issue I called bullshit on: that there is no
> >> such thing as a gaussian blur that "matches" motion blur. The width
> >> of a motion blur, in pixels, depends entirely on how fast the
> >> objects in the picture are moving. The artificial blur applied to
> >> pal/ntsc conversion is INDEPENDENT of motion blur!
> >
> > /shrug
> >
> > Eventually all TVs will be 1080p (or better), and capable of
> > displaying both 1080i, and 720p (with simple resolution scaling)
> > eliminating the need to 'convert' between them.
> >
> > Further, I -hope- eventually TVs will be able to accept, and display
> > content at its source fps rate, so we won't be converting between 24,
> > 50 or 60 fps rates. The broadcaster broadcasts at what rate it was
> > recorded in, and the TV displays whats coming in at -that- rate.
> >
> > (I suppose to prevent there being a 'jar' in the aesthetics of the
> > picture, commericals should be converted and encoded to match the same
> > resolution and fps rate as the surrounding content...)
>
> Hmm....my Mits converts my OTA FOX signal to 1080i. I guess it's better
> than rejecting it all together......

Definately.

My point was largely that the issues between converting from 720p to
1080i and back again, is an ephemeral problem at most. Soon it will all
go to 1080p or better, and the issues really just go away. I don't
really want manufacturers to spend a lot of time refining the 720p->
1080i (or back again) conversion algorithms... just get on with
delivering affordable 1080p sets and convert to that.

> That's what I get for buying too early. No 720p or 1080p support, no
> DVI........of course, it is a good reason to upgrade!

Its a computer now. It was obsolete before you plugged it in.

 

[Guest]

Archived from groups: alt.tv.tech.hdtv (More info?)

42 wrote:
> In article <G7idnVsT8NAUO3HcRVn-iw@comcast.com>, alpertl@xxcomcast.net
> says...
>
> Its a computer now. It was obsolete before you plugged it in.

Ya know, if you think about it, it's almost as expensive as computer
equipment when memory was running +$100 a meg using 9 single dram chips and
20 meg hard drives were huge is size and cost.......

Oy, these tech hobbies are always expensive. I'm surprised the wife has put
up with me for so long....don't feed the baby, daddy needs a new video card!