is this true? resolution myths? - Page 4

SeeMoreDigital · 29th September 2003, 09:49

Hey Joe! (sorry I could'nt resist)

I'm so glad you wrote this. I took pen to paper myself trying to come up with an 'easy to understand' version of how resolution was measured in the old days.... but my version ran to quite a few hundred words and was still not as simple to understand as your post!

I think I really should have paid more attention in my English lessons at school. But it was a long time ago. And was also at a time when 'typing' was considered a 'girly' thing to do.... And look at me now!

My, how times have changed!

Cheers

ppera2 · 29th September 2003, 12:51

Very good explanation, Jeo Fenton.

Is there some research about how human perception sees vertical lines on progressive scan monitors? I think that it should be little better case (more %).

Btw. that about bandwith, and sine form by higher freq. stays for VGA monitors and cards too. Therefore are so high freq. of RAMDAC's and high bandwiths of monitors.

SeeMoreDigital · 29th September 2003, 13:32

Hi ppera2,

Quote:

Is there some research about how human perception sees vertical lines on progressive scan monitors? I think that it should be little better case (more %).

Joe mentioned at the beginning of his post "Back when TVs were actually made from 100% analog parts (you know, transistors, tubes - that sort of thing) you didn't have dots or pixels, you had frequencies and bandwidth"

Todays TV and PC monitors are totally different pieces of equipment. So much so infact, I would probably be right in thinking that there's not a single TV or PC monitor that does not process the video digitally at some stage!

Personally I hate 100Hz (digital) processing on modern TV's. As to me, the presented image looks like a 'water colour painting'. It just does'nt look real!

My parents have just been conned into buying a 100Hz 32" widescreen Panasonic 100Hz TV. And to me, the picture looks crap!

Cheers

Kika · 29th September 2003, 13:36

Quote:

And to me, the picture looks crap!

On most 100Hz-TVs you are able to disable the Digital Image-Processing (like Noise-Reduction and other Stuff).
Turn this Features of, and the picture might be much more look natural.

SeeMoreDigital · 29th September 2003, 14:13

Thanks Kika,

I did actually try 'all' the different Panasonic settings. And the picture still looked crap!

At the time my father was watching a live golf broadcast. And it's the first time I've seen grass without individual blades.

I even thought of visiting a garden centre to find out if this 'new' type of grass was available to buy. As it would be far easier to maintain!

Seriously though, the only decent 100Hz processing TV's I've seen have been by Philips!

Oh, and another bad thing about the Panasonic. Why does it always want to alter the aspect ratio of a 4:3 image to fit the 16:9 screen. You just can't turn this function 'off' either!

Cheers

r6d2 · 29th September 2003, 16:18

Hi guys,

I though you might me interested in this. Trying different frame sizes on my TV I found that using 480x480 (SVCD) only revealed enough detail pertaining to CVD (352x480). Only if using non standard frame sizes like 528x480 or 544x480 I could see the detail a typical SVCD frame size was encoding.

This has to do with something similiar to what @Joe Fenton explained about vertical resolution on a previous post, but horizontally.

I built a small tool to measure the horizontal resolution which may be of use to you. Please check it out at:

http://forum.doom9.org/showthread.ph...891#post378891

SeeMoreDigital · 29th September 2003, 16:35

Quote:

Originally posted by r6d2
... Trying different frame sizes on my TV I found that using 480x480 (SVCD) only revealed enough detail pertaining to CVD (352x480). Only if using non standard frame sizes like 528x480 or 544x480 I could see the detail a typical SVCD frame size was encoding...

You can perform the same 'horizontal scaling' tests with DivX. Take any PAL DVD and rip a 'fast action' chapter from it. Then encode the chapter at 900kbps 2pass VBR using 720x576 'anamorphic frame' pixels. And then again at 1024x576 'true frame' pixels.

Then report back which one looks best!

For some reason you can only do this with PAL pixel frame sizes. 854x480 NTSC pixel frame sizes (or it's near 16 pixel equivalent) just don't work!

Cheers

r6d2 · 29th September 2003, 16:57

Quote:

Originally posted by SeeMoreDigital
Then report back which one looks best!

Sorry, I don't do DivX since I cannot play them on my TV, and I don't have access to PAL sources. I was just interested in measuring the horizontal resolution, for which I built a pattern image.

SeeMoreDigital · 29th September 2003, 17:04

Quote:

Originally posted by r6d2
Sorry, I don't do DivX since I cannot play them on my TV, and I don't have access to PAL sources. I was just interested in measuring the horizontal resolution, for which I built a pattern image.

Shame. Maybe other forum members can confirm!

I forgot to mention that this 'trick' it also works with low bitrate Mpeg1 encodes too (never tried with Mpeg2)!

Cheers

ppera2 · 29th September 2003, 17:55

Quote:

Originally posted by SeeMoreDigital

Todays TV and PC monitors are totally different pieces of equipment. So much so infact, I would probably be right in thinking that there's not a single TV or PC monitor that does not process the video digitally at some stage!
Cheers

I wouldn't agree that fact that todays monitors have many digital parts has much influence on still analogue nature of VGA video.

Video can be processed digitally, but it still wont change that final stage amplifier, which goes to pic tube is analogue. So, all about bandwith stays.

Just to say, that I work as servicer of TV's and monitors, and I know how them are built.

SeeMoreDigital · 29th September 2003, 18:14

Quote:

Originally posted by ppera2
.... Just to say, that I work as servicer of TV's and monitors, and I know how them are built.

I service and repair all our equipment too. So I don't understand why you don't agree that most if not all PC monitors and TV's don't digitize some element of an inputed signal!

Cheers

Joe Fenton · 29th September 2003, 21:07

I worked one summer as a TV repairman back when TVs were moving from transistors to ICs. Quasars and RCA were our bane, while Sylvania and Philco were a joy to work on.

Unless you have a pulse-width-modulated LCD or plasma display panel, all displays eventually have to convert the signal back to analog before reaching the CRT. The problem with properly displaying a squarewave is exactly why computer monitors have such a high bandwidth. Consider a monitor trying to display 640 pixels horizontally at 60Hz vertical refresh rate. 640 pixels displays 320 lines, but we want them to be crisp pixels, not barely discernable lines, so we need to allow for a seventh harmonic. So 320 / 80 X 2 X 7 = 56 MHz.

As to progressive vs. interlaced, there are more studies being performed now that prgressive scan monitors of decent size are available. I was able to find this:

Quote:

Interlace has been introduced in the beginning of television broadcast for good reasons. The spectrum that can be displayed with interlace is well adapted to the Human Visual System (HVS), and the use of interlace reduced the required channel capacity. However, interlaced video signals suffer from various artifacts. Already in the beginning of the thirties, Engstrom [6] revealed the effect of line flicker, i.e. flickering that appears at horizontal edges in the image. Another effect associated with interlace is line crawl, which becomes visible when the eye scans the picture vertically at a speed of an odd number of scanning lines per field. The structure of the scanning becomes visible and it seems to ‘crawl’ across the picture. And as a third deficiency, interlace reduces the vertical resolution (only) in case of vertical camera or object motion.

On the other hand, an interlaced signal has twice the vertical resolution in comparison to the progressive video signal, for non-vertical moving image parts. Only in case of so-called critical velocities (odd vertical velocities), the vertical resolution drops to the same resolution as the progressive format as illustrated in Figure 2. As an example, a progressive video signal with 625 scanning lines requires the same sampling frequency as an interlaced video signal with 1250 scanning lines.

So, stationary pictures, e.g. down-loaded from the Internet, Teletext, or receiver–side generated graphics, could profit from the superior vertical resolution of an interlaced display format. It is, however, not obvious, that such an interlaced format is also (perceptually) preferred. The advantage of the increased vertical resolution of the interlaced scanning format is payed with possibly annoying line flicker on the display. A decent comparison between the various options is lacking in the literature so far, probably because a high quality video format conversion at a consumer price level is only available recently.

SeeMoreDigital · 29th September 2003, 21:15

Hi Joe,

I think you must be as old as I am!

I'll show you mine. If you show me yours!

Cheers

ppera2 · 29th September 2003, 21:15

Quote:

Originally posted by SeeMoreDigital
I service and repair all our equipment too. So I don't understand why you don't agree that most if not all PC monitors and TV's don't digitize some element of an inputed signal!
Cheers

Perhaps you should read my post more carefully. And then, perhaps you will not claim something what I didn't write.

SeeMoreDigital · 29th September 2003, 21:31

ppera2

I'm sorry if I have upset or confused you or even become confused myself!

I'm not a big fan of digital technology because of it's 'big brother' abilities.

My biggest fear is that when CRT screens disappear altogether in favour of flat plasma, LCD etc screens, there will be no need to have any analog element at all.

When this happens. And it will! Even the screens themselves could be used as encryption tools. As it's very easy for a chip to be programmed and then instruct which pixel goes/appears where!

Cheers

Joe Fenton · 30th September 2003, 05:08

Quote:

Originally posted by SeeMoreDigital
Hi Joe,

I think you must be as old as I am!

I'll show you mine. If you show me yours!

Cheers

38 and feeling every bit of it.

Analog displays still have quite a bit of life yet. As far as flat screens go, cold cathode emission displays can still take back the crown from LCD and plasma display, especially considering the short life span on those two technologies. Plasma displays in particular start to lose cells in as little as five years. They will get better, but analog display technologies will only get cheaper as time passes. Why should I buy a 17" LCD display for $330 when I can get a 17" CRT for $110? I just noticed, 15" LCDs now under $200. Boy, they've come a long way from when they were first released.

SeeMoreDigital · 30th September 2003, 11:35

Quote:

Originally posted by Joe Fenton
38 and feeling every bit of it.

Analog displays still have quite a bit of life yet. As far as flat screens go, cold cathode emission displays can still take back the crown from LCD and plasma display, especially considering the short life span on those two technologies. Plasma displays in particular start to lose cells in as little as five years. They will get better, but analog display technologies will only get cheaper as time passes. Why should I buy a 17" LCD display for $330 when I can get a 17" CRT for $110? I just noticed, 15" LCDs now under $200. Boy, they've come a long way from when they were first released.

41! I think I win there. Or should that be lose!!!

I have first hand experience with regard to plasma cell degradation as we have 2no 42" screens, at the moment. I have to admit we did not feel the need to spend large amounts of money on them because they are used at exhibitions, seminars or presentations. And as such are moved around quite a bit!

It is good to see the prices of LCD and plasmas fall. But as usual the manufactureres have started tempting us with new, high definition 'XGA' models. And boy do these look good!

Well out of my price range though.... at the moment!

Cheers

ppera2 · 30th September 2003, 15:51

Quote:

Originally posted by SeeMoreDigital
ppera2
I'm sorry if I have upset or confused you or even become confused myself!...

No upsession, I'm too old for such things (48)

I don't think that they will implement some heavy protections in displays soon - it must have first some standard to be worldwide etc...

Kika · 30th September 2003, 16:01

Hey, let's build the "League of Extraordinary (old) Gentlemen".

I'm 40...

SeeMoreDigital · 30th September 2003, 16:45

I wonder if Doom9 will ever reveal his (or maybe her) age?

Maybe Doom9 isn't a person at all. Could be a supercomputer. A digital super spy!

How about a "League of Extraordinary (old) Farts"

Cheers

29th September 2003, 09:49	#61 \| Link
SeeMoreDigital Life's clearer in 4K UHD Join Date: Jun 2003 Location: Notts, UK Posts: 12,227	Hey Joe! (sorry I could'nt resist) I'm so glad you wrote this. I took pen to paper myself trying to come up with an 'easy to understand' version of how resolution was measured in the old days.... but my version ran to quite a few hundred words and was still not as simple to understand as your post! I think I really should have paid more attention in my English lessons at school. But it was a long time ago. And was also at a time when 'typing' was considered a 'girly' thing to do.... And look at me now! My, how times have changed! Cheers __________________ \| I've been testing hardware media playback devices and software A/V encoders and decoders since 2001 \| My Network Layout & A/V Gear \|

29th September 2003, 12:51	#62 \| Link
ppera2 Registered User Join Date: Oct 2001 Location: Lands of confusion Posts: 1,217	Very good explanation, Jeo Fenton. Is there some research about how human perception sees vertical lines on progressive scan monitors? I think that it should be little better case (more %). Btw. that about bandwith, and sine form by higher freq. stays for VGA monitors and cards too. Therefore are so high freq. of RAMDAC's and high bandwiths of monitors. __________________ Informational value of an advert is in inverted proportion to beauty of playing model(s)/actress(es)

29th September 2003, 14:13	#65 \| Link
SeeMoreDigital Life's clearer in 4K UHD Join Date: Jun 2003 Location: Notts, UK Posts: 12,227	Thanks Kika, I did actually try 'all' the different Panasonic settings. And the picture still looked crap! At the time my father was watching a live golf broadcast. And it's the first time I've seen grass without individual blades. I even thought of visiting a garden centre to find out if this 'new' type of grass was available to buy. As it would be far easier to maintain! Seriously though, the only decent 100Hz processing TV's I've seen have been by Philips! Oh, and another bad thing about the Panasonic. Why does it always want to alter the aspect ratio of a 4:3 image to fit the 16:9 screen. You just can't turn this function 'off' either! Cheers __________________ \| I've been testing hardware media playback devices and software A/V encoders and decoders since 2001 \| My Network Layout & A/V Gear \|

29th September 2003, 16:18	#66 \| Link
r6d2 Graphite mod Join Date: May 2003 Location: Away Posts: 2,022	Tool to measure horizontal resolution Hi guys, I though you might me interested in this. Trying different frame sizes on my TV I found that using 480x480 (SVCD) only revealed enough detail pertaining to CVD (352x480). Only if using non standard frame sizes like 528x480 or 544x480 I could see the detail a typical SVCD frame size was encoding. This has to do with something similiar to what @Joe Fenton explained about vertical resolution on a previous post, but horizontally. I built a small tool to measure the horizontal resolution which may be of use to you. Please check it out at: http://forum.doom9.org/showthread.ph...891#post378891 __________________ MPEG4 quality with MPEG2? - Try the Poor Man's DVD. FACAR - As seen on TV! - The Complete Idiot's Guide to a good DVD Conversion. Time is money. Try D2Sroba for DVD2SVCD (FAQ) and save both. All electricity bills supported! Do you know how much overscan and which resolution your TV has? Find out if NTSC. Moderator: 1: one who arbitrates 2: one who presides over an assembly, meeting, or discussion 3: a substance (as graphite) used for slowing down neutrons in a nuclear reactor (Webster)

29th September 2003, 21:15	#73 \| Link
SeeMoreDigital Life's clearer in 4K UHD Join Date: Jun 2003 Location: Notts, UK Posts: 12,227	Hi Joe, I think you must be as old as I am! I'll show you mine. If you show me yours! Cheers __________________ \| I've been testing hardware media playback devices and software A/V encoders and decoders since 2001 \| My Network Layout & A/V Gear \|

29th September 2003, 21:31	#75 \| Link
SeeMoreDigital Life's clearer in 4K UHD Join Date: Jun 2003 Location: Notts, UK Posts: 12,227	ppera2 I'm sorry if I have upset or confused you or even become confused myself! I'm not a big fan of digital technology because of it's 'big brother' abilities. My biggest fear is that when CRT screens disappear altogether in favour of flat plasma, LCD etc screens, there will be no need to have any analog element at all. When this happens. And it will! Even the screens themselves could be used as encryption tools. As it's very easy for a chip to be programmed and then instruct which pixel goes/appears where! Cheers __________________ \| I've been testing hardware media playback devices and software A/V encoders and decoders since 2001 \| My Network Layout & A/V Gear \|

30th September 2003, 16:01	#79 \| Link
Kika Registered User Join Date: Jul 2002 Location: Germany Posts: 819	Hey, let's build the "League of Extraordinary (old) Gentlemen". I'm 40...

30th September 2003, 16:45	#80 \| Link
SeeMoreDigital Life's clearer in 4K UHD Join Date: Jun 2003 Location: Notts, UK Posts: 12,227	I wonder if Doom9 will ever reveal his (or maybe her) age? Maybe Doom9 isn't a person at all. Could be a supercomputer. A digital super spy! How about a "League of Extraordinary (old) Farts" Cheers __________________ \| I've been testing hardware media playback devices and software A/V encoders and decoders since 2001 \| My Network Layout & A/V Gear \|