|
|
High Definition TV questions
1) Are Hi-Definition DVD's available and if so can I play them on my DVD
Re-Writer with my present hardware and software ? 2) Does the system use Anamophic Windscreen or true Windscreen ? 3) Is the colour of the same resolution as the luminance or is it half the resolution or worse like PAL ? |
Agamemnon wrote:
2) Does the system use Anamophic Windscreen or true Windscreen ? Can you please explain what you think the difference is ? |
"Mark Carver" wrote in message ... Agamemnon wrote: 2) Does the system use Anamophic Windscreen or true Windscreen ? Can you please explain what you think the difference is ? True Widescreen = 1265 x 768 individual pixels Anamophic = 1024 x 768 individual pixels |
Agamemnon wrote:
1) Are Hi-Definition DVD's available No. and if so can I play them on my DVD Re-Writer with my present hardware and software ? No. 3) Is the colour of the same resolution as the luminance or is it half the resolution or worse like PAL ? Dunno, but I doubt you'll be complaining about quality. -- Steve - www.digitalradiotech.co.uk - Digital Radio News & Info Find the cheapest MP3 player, Freeview and DAB prices: http://www.digitalradiotech.co.uk/mp3_players.htm http://www.digitalradiotech.co.uk/fr..._receivers.htm http://www.digitalradiotech.co.uk/da...tal_radios.htm |
Agamemnon wrote:
: True Widescreen = 1265 x 768 individual pixels : Anamophic = 1024 x 768 individual pixels I think you meant 1365, not 1265, but in any case none of those figures have anything to do with broadcast HDTV which is either 1920 x 1080 pixels or 1280 x 720 pixels. P.S. the word is "anamorphic" (with an 'r'). Richard. http://www.rtrussell.co.uk/ To reply by email change 'news' to my forename. |
Agamemnon wrote:
1) Are Hi-Definition DVD's available and if so can I play them on my DVD Re-Writer with my present hardware and software ? *consults crystal ball* Hmm well I'm afraid my Crystal Ball doesn't know what hardware and software you have. 2) Does the system use Anamophic Windscreen or true Windscreen ? It uses Car Windscreen. 3) Is the colour of the same resolution as the luminance or is it half the resolution or worse like PAL ? It's the same as any other mpeg2 source. |
Agamemnon wrote:
1) Are Hi-Definition DVD's available and if so can I play them on my DVD Re-Writer with my present hardware and software ? There are some high definition DVDs of dolphins and people exploring caves and stuff available in microsoft VC9 format, which is one of the mandatory formats (along with H264 and MPEG2) for HD-DVD and Blu-ray DVD. These will play with windows media player on a high-spec PC. There are samples free to download from the microsoft website. 2) Does the system use Anamophic Windscreen or true Windscreen ? the resolutions are 1920x1080 or 1280x720, both of which are 16:9, so yes its not anamorphic 3) Is the colour of the same resolution as the luminance or is it half the resolution or worse like PAL ? I assume VC9 and H264 are the same as MPEG2 in this respect |
"Mark Carver" wrote in message
... Agamemnon wrote: 2) Does the system use Anamophic Windscreen or true Windscreen ? Can you please explain what you think the difference is ? Square pixels dear boy, when the world is HD the broadcasters can stick their dastardly elongated SD pels somewhere North of their VBI ;) Az. |
Aztec wrote:
"Mark Carver" wrote in message ... Agamemnon wrote: 2) Does the system use Anamophic Windscreen or true Windscreen ? Can you please explain what you think the difference is ? Square pixels dear boy, when the world is HD the broadcasters can stick their dastardly elongated SD pels somewhere North of their VBI ;) Ah, I see, that's what Mr Armageddon was getting at, well all HD resolutions are native 16:9 are they not ? |
"Mark Carver" wrote in message
... Aztec wrote: "Mark Carver" wrote in message ... Agamemnon wrote: 2) Does the system use Anamophic Windscreen or true Windscreen ? Can you please explain what you think the difference is ? Square pixels dear boy, when the world is HD the broadcasters can stick their dastardly elongated SD pels somewhere North of their VBI ;) Ah, I see, that's what Mr Armageddon was getting at, well all HD resolutions are native 16:9 are they not ? Yes, the main one's are. However you see stuff like 1080x1440, as used in Australia due to bandwidth constraints, also seen in the US when some affiliates are wielding their shoehorn. Az. |
We haven't really added to the fund of human knowledge in this thread
have we? The real issue the OP was addressing was are HD DVDs available. The proper answer is no not yet. As one poster said there are some naff M$ titles available for download more or less as "proof of concept". No movies apart from Oklahoma (was it?) & standing in the Shadows of Motown are yet available. Once Blu-ray becomes available more titles are likely to be issued but not yet. We seem to have totally lost the plot when it comes to resolution. There are several different schemes proposed though none are either in use or set in stone (yet). No one (I think) really addressed the 3rd question regarding colour resolution. Perhaps, like me, people did not really understand the question. I guess, the true answer is that it is far too soon to be asking detailed questions like this when the technology is still evolving & there is no real software (DVDs - or are they firmware?) yet available. In article , Aztech writes "Mark Carver" wrote in message ... Aztec wrote: "Mark Carver" wrote in message ... Agamemnon wrote: 2) Does the system use Anamophic Windscreen or true Windscreen ? Can you please explain what you think the difference is ? Square pixels dear boy, when the world is HD the broadcasters can stick their dastardly elongated SD pels somewhere North of their VBI ;) Ah, I see, that's what Mr Armageddon was getting at, well all HD resolutions are native 16:9 are they not ? Yes, the main one's are. However you see stuff like 1080x1440, as used in Australia due to bandwidth constraints, also seen in the US when some affiliates are wielding their shoehorn. Az. -- Keith Bailey |
On Mon, 15 Nov 2004 12:44:15 +0000, Mark Carver
wrote: Agamemnon wrote: 2) Does the system use Anamophic Windscreen or true Windscreen ? Can you please explain what you think the difference is ? The wipers are a different shape. |
Keith Bailey wrote:
We haven't really added to the fund of human knowledge in this thread have we? The real issue the OP was addressing was are HD DVDs available. The proper answer is no not yet. As one poster said there are some naff M$ titles available for download more or less as "proof of concept". No movies apart from Oklahoma (was it?) & standing in the Shadows of Motown are yet available. Once Blu-ray becomes available more titles are likely to be issued but not yet. There is Terminator 2 of course, but the DRM is server based and you have to have a US IP address (not a known proxy). We seem to have totally lost the plot when it comes to resolution. There are several different schemes proposed though none are either in use or set in stone (yet). The standard for HD DVDs will virtually have to be the same as that for HDTV, i.e. 1280x720 60/50p or 1920x1080 30/25i. Its possible that 1920x1080 60/50p might be included in the standard for future proofing, and it would be great if they mandated 1920x1080 24p, but I bet they don't. No one (I think) really addressed the 3rd question regarding colour resolution. Perhaps, like me, people did not really understand the question. I think the OP was referring to the fact that in PAL the vertical chrominance resolution is only half that of the luminance resolution. Digital doesn't do that sort of thing. I guess, the true answer is that it is far too soon to be asking detailed questions like this when the technology is still evolving & there is no real software (DVDs - or are they firmware?) yet available. As far as I know, the only thing thats actually been decided on is the compression standards that are going to be mandated, which is basically all of them ;-) |
"Keith Bailey" wrote in message
... We haven't really added to the fund of human knowledge in this thread have we? He asked whether they will be anamorphic or not, we've nicely explained HD formats are generally square pixels. If this went over your head I can only apologise. The real issue the OP was addressing was are HD DVDs available. The proper answer is no not yet. As one poster said there are some naff M$ titles available for download more or less as "proof of concept". No movies apart from Oklahoma (was it?) & standing in the Shadows of Motown are yet available. Once Blu-ray becomes available more titles are likely to be issued but not yet. People can import D-VHS right now, there's various D-Theater titles out. There are also various HD stuff about on plain old DVD-9 discs with full length movies encoded in WM9. Terminator 2 is released as dual disc WMVHD. We seem to have totally lost the plot when it comes to resolution. There are several different schemes proposed though none are either in use or set in stone (yet). 1080i or 720p, or with provision for both, it doesn't seem too contentious, certainly not off the plot. The choice of codec is a different matter, the official HD-DVD spec includes provision for a multitude of codecs including AVC. The BD-ROM group seem quite fond of MPEG2. No one (I think) really addressed the 3rd question regarding colour resolution. Perhaps, like me, people did not really understand the question. He's refering to colour subsampling, as far as I'm aware it will remain 4:2:0, there was some talk of 4:2:2 but this has to be weighed against what people are most critical about, resolution and artefacts are higher up the list. Az. |
In article , Ben
wrote: No one (I think) really addressed the 3rd question regarding colour resolution. Perhaps, like me, people did not really understand the question. I think the OP was referring to the fact that in PAL the vertical chrominance resolution is only half that of the luminance resolution. Digital doesn't do that sort of thing. People who think this is important don't understand the question. All the analogue colour encoding systems have less than half the horizontal chrominance resolution anyway, because that's all that's required, so reducing the vertical resolution to match will do no harm at all. All these systems are designed to take account of the way the human visual system works and not waste bandwidth by transmitting information that nobody will see. Rod. |
I would like the best pictures that could be got out the present digital
systems NOW. But the broadcasters do not appear to want to do that. So why bother with new systems, new TV sets, new DVD players etc that would be required for us to purchase. I could not trust the broadcasters to use a new sysyem to its best on what they do today. -- Regards, David Please reply to News Group. |
"Roderick Stewart" wrote in message om... In article , Ben wrote: No one (I think) really addressed the 3rd question regarding colour resolution. Perhaps, like me, people did not really understand the question. I think the OP was referring to the fact that in PAL the vertical chrominance resolution is only half that of the luminance resolution. Digital doesn't do that sort of thing. People who think this is important don't understand the question. All the analogue colour encoding systems have less than half the horizontal chrominance resolution anyway, because that's all that's required, so reducing the vertical resolution to match will do no harm at all. All these systems are designed to take account of the way the human visual system works and not waste bandwidth by transmitting information that nobody will see. The human visual system does not work like that at all either at close range or in bright light. The centre of your field of view is more densely packed with colour receptors than B/W and because of this it provides the highest resolution image and that's what gives you the ability to read. If what you are saying was done on a computer display it would be completely intolerable. Its bad enough trying to read coloured text on a dark background as it is. If a system were not designed with 1:1 colour to pixel mapping I would not accept it to be Hi-Dfeinition. In fact I would prefer as 625 line with 1:1 mapping to any 1050 or 720 line system without it. If you compare a 768x576 DVD screen capture with a scanned image from a magazine or digital camera the difference in quality is astonishing. Rod. |
In article , Agamemnon
wrote: People who think this is important don't understand the question. All the analogue colour encoding systems have less than half the horizontal chrominance resolution anyway, because that's all that's required, so reducing the vertical resolution to match will do no harm at all. All these systems are designed to take account of the way the human visual system works and not waste bandwidth by transmitting information that nobody will see. The human visual system does not work like that at all either at close range or in bright light. The centre of your field of view is more densely packed with colour receptors than B/W and because of this it provides the highest resolution image and that's what gives you the ability to read. Concentration of receptor cells is irrelevant. I was talking about what the eye perceives. Choice of chrominance bandwidth for NTSC, PAL and SECAM colour systems, i.e all the main broadcast systems, was based on research that showed that visual acuity is less for changes in colour than for changes in brightness. All these TV systems use this presumption and only transmit chroma with about one third of the bandwidth used for luminance and they all work. At the intended viewing distance you can't see that the colour iunformation is less sharp. Rod. |
"Roderick Stewart" wrote in message om... In article , Agamemnon wrote: People who think this is important don't understand the question. All the analogue colour encoding systems have less than half the horizontal chrominance resolution anyway, because that's all that's required, so reducing the vertical resolution to match will do no harm at all. All these systems are designed to take account of the way the human visual system works and not waste bandwidth by transmitting information that nobody will see. The human visual system does not work like that at all either at close range or in bright light. The centre of your field of view is more densely packed with colour receptors than B/W and because of this it provides the highest resolution image and that's what gives you the ability to read. Concentration of receptor cells is irrelevant. I was talking about what the eye perceives. Choice of chrominance bandwidth for NTSC, PAL and SECAM colour What the eye perceives is down to the concentration of receptor cells. systems, i.e all the main broadcast systems, was based on research that showed that visual acuity is less for changes in colour than for changes in brightness. All these TV systems use this presumption and only transmit chroma In bright light the eye is more sensitive to colour information and in dim light it can't see colour at all and relies on peripheral black and white vision. That's why you are more likely to see dim stars by not looking at them directly but to the side. On top of that if two colours are placed next to each other the brain will merge them into another colour if you are looking from far away. with about one third of the bandwidth used for luminance and they all work. At the intended viewing distance you can't see that the colour iunformation is less sharp. If you wish to invoke intended viewing distance then going by what you have just said at this distance you cant see the difference between normal definition TV and high definition TV either so why bother with high defintion TV, since if as you claim you can only perceive 293 pixels of colour on a 768 column display then doubling that to 768 pixels on a 1572 column display will have no noticeable effect on effect the colour or even the intensity definition either. Obviously the fact that people are developing high definition TV shows that the difference is noticeable which more or less proves that the so-called research into colour perception you are referring to is a load of baloney even at the intended viewing distance. As far as I am concerned the intended viewing distance is me sitting right in front of my monitor and I can read colour text at 1600x1200 resolution well enough and I can see the individual colours and I can see the blurring caused by halving the colour resolution perfectly well and I can't stand it. I'd prefer a lower screen resolution without any compromise to the colour bandwidth than a higher screen resolution with the colour bandwidth halved. Rod. |
"Agamemnon" wrote in message ... "Roderick Stewart" wrote in message om... In article , Agamemnon wrote: People who think this is important don't understand the question. All the analogue colour encoding systems have less than half the horizontal chrominance resolution anyway, because that's all that's required, so reducing the vertical resolution to match will do no harm at all. All these systems are designed to take account of the way the human visual system works and not waste bandwidth by transmitting information that nobody will see. The human visual system does not work like that at all either at close range or in bright light. The centre of your field of view is more densely packed with colour receptors than B/W and because of this it provides the highest resolution image and that's what gives you the ability to read. Concentration of receptor cells is irrelevant. I was talking about what the eye perceives. Choice of chrominance bandwidth for NTSC, PAL and SECAM colour What the eye perceives is down to the concentration of receptor cells. systems, i.e all the main broadcast systems, was based on research that showed that visual acuity is less for changes in colour than for changes in brightness. All these TV systems use this presumption and only transmit chroma In bright light the eye is more sensitive to colour information and in dim light it can't see colour at all and relies on peripheral black and white vision. That's why you are more likely to see dim stars by not looking at them directly but to the side. On top of that if two colours are placed next to each other the brain will merge them into another colour if you are looking from far away. with about one third of the bandwidth used for luminance and they all work. At the intended viewing distance you can't see that the colour iunformation is less sharp. If you wish to invoke intended viewing distance then going by what you have just said at this distance you cant see the difference between normal definition TV and high definition TV either so why bother with high defintion TV, since if as you claim you can only perceive 293 pixels of calculator malefaction or bad top row typing, 384 pixels colour on a 768 column display then doubling that to 768 pixels on a 1572 where on earth did I get 1572 from, is 1536. Is Microsoft's calculator bugged ? column display will have no noticeable effect on effect the colour or even the intensity definition either. Obviously the fact that people are developing high definition TV shows that the difference is noticeable which more or less proves that the so-called research into colour perception you are referring to is a load of baloney even at the intended viewing distance. As far as I am concerned the intended viewing distance is me sitting right in front of my monitor and I can read colour text at 1600x1200 resolution well enough and I can see the individual colours and I can see the blurring caused by halving the colour resolution perfectly well and I can't stand it. I'd prefer a lower screen resolution without any compromise to the colour bandwidth than a higher screen resolution with the colour bandwidth halved. Rod. |
"Agamemnon" wrote in message ... "Roderick Stewart" wrote in message om... In article , Ben wrote: No one (I think) really addressed the 3rd question regarding colour resolution. Perhaps, like me, people did not really understand the question. I think the OP was referring to the fact that in PAL the vertical chrominance resolution is only half that of the luminance resolution. Digital doesn't do that sort of thing. People who think this is important don't understand the question. All the analogue colour encoding systems have less than half the horizontal chrominance resolution anyway, because that's all that's required, so reducing the vertical resolution to match will do no harm at all. All these systems are designed to take account of the way the human visual system works and not waste bandwidth by transmitting information that nobody will see. The human visual system does not work like that at all either at close range or in bright light. The centre of your field of view is more densely packed with colour receptors than B/W and because of this it provides the highest resolution image and that's what gives you the ability to read. I think there are millions more rods and they're more senstive, of the smaller number of cones only around 2% of cones have blue sensitivity for example. You can make a lot more valuable use of bandwidth in terms of resolution than providing a 4:4:4 colour space. I would say compression artefacts or even curious P frames are a lot more obvious than quantization at 4:2:0. Az. |
"Aztech" wrote in message ... "Agamemnon" wrote in message ... "Roderick Stewart" wrote in message om... In article , Ben wrote: No one (I think) really addressed the 3rd question regarding colour resolution. Perhaps, like me, people did not really understand the question. I think the OP was referring to the fact that in PAL the vertical chrominance resolution is only half that of the luminance resolution. Digital doesn't do that sort of thing. People who think this is important don't understand the question. All the analogue colour encoding systems have less than half the horizontal chrominance resolution anyway, because that's all that's required, so reducing the vertical resolution to match will do no harm at all. All these systems are designed to take account of the way the human visual system works and not waste bandwidth by transmitting information that nobody will see. The human visual system does not work like that at all either at close range or in bright light. The centre of your field of view is more densely packed with colour receptors than B/W and because of this it provides the highest resolution image and that's what gives you the ability to read. I think there are millions more rods and they're more senstive, of the smaller number of cones only around 2% of cones have blue sensitivity for example. You can make a lot more valuable use of bandwidth in terms of resolution than providing a 4:4:4 colour space. I would say compression artefacts or even curious P frames are a lot more obvious than quantization at 4:2:0. OK I've done a simulation taking a scanned image and converting it to separate H, S, L frames and then applying 50% compression to the horizontal hue and the stretching it back again and then recombining the images and the colour artefacts are only obvious if I magnify the image by 2. If I also did another experiments and compressed the both the saturation and the hue by the same amount the recombined image shows noticeable shimmering at the edges of objects but its not as bad as the stuff I have watched on DVD which on my PC which is completely blurred compared to scans and digital camera photos at the same resolution. Even a full screen facial portrait looks blurred. Is something else other than the colour being compressed and if so by how much ? Is dynamic range compression being applied to the colour or luminance or saturation. How may bits per pixel are being used. Az. |
"Agamemnon" wrote in message news:419a4fa8$0
I think there are millions more rods and they're more senstive, of the smaller number of cones only around 2% of cones have blue sensitivity for example. You can make a lot more valuable use of bandwidth in terms of resolution than providing a 4:4:4 colour space. I would say compression artefacts or even curious P frames are a lot more obvious than quantization at 4:2:0. OK I've done a simulation taking a scanned image and converting it to separate H, S, L frames and then applying 50% compression to the horizontal hue and the stretching it back again and then recombining the images and the colour artefacts are only obvious if I magnify the image by 2. So much for filtering. If I also did another experiments and compressed the both the saturation and the hue by the same amount the recombined image shows noticeable shimmering at the edges of objects but its not as bad as the stuff I have watched on DVD which on my PC which is completely blurred compared to scans and digital camera photos at the same resolution. Even a full screen facial portrait looks blurred. Is something else other than the colour being compressed and if so by how much ? Is dynamic range compression being applied to the colour or luminance or saturation. How may bits per pixel are being used. 24-bit colour space. http://tinyurl.com/4wnhq Az. |
"Aztech" wrote in message ... "Agamemnon" wrote in message news:419a4fa8$0 I think there are millions more rods and they're more senstive, of the smaller number of cones only around 2% of cones have blue sensitivity for example. You can make a lot more valuable use of bandwidth in terms of resolution than providing a 4:4:4 colour space. I would say compression artefacts or even curious P frames are a lot more obvious than quantization at 4:2:0. OK I've done a simulation taking a scanned image and converting it to separate H, S, L frames and then applying 50% compression to the horizontal hue and the stretching it back again and then recombining the images and the colour artefacts are only obvious if I magnify the image by 2. So much for filtering. It depends how you do the compression. I did a pixel resize. With a Bilinear resample the artefacts are massive and obvious a mile away and this was when just the hue was compressed. The filters are probably what are causing the blurring then. If I also did another experiments and compressed the both the saturation and the hue by the same amount the recombined image shows noticeable shimmering at the edges of objects but its not as bad as the stuff I have watched on DVD which on my PC which is completely blurred compared to scans and digital camera photos at the same resolution. Even a full screen facial portrait looks blurred. Is something else other than the colour being compressed and if so by how much ? Is dynamic range compression being applied to the colour or luminance or saturation. How may bits per pixel are being used. 24-bit colour space. http://tinyurl.com/4wnhq Az. |
In article , Agamemnon
wrote: What the eye perceives is down to the concentration of receptor cells. Not entirely. The eye isn't a camera, or a measuring instrument. It has a brain attached. The combination of the two has evolved to process information that is significant to their owner, who then judges it subjectively. systems, i.e all the main broadcast systems, was based on research that showed that visual acuity is less for changes in colour than for changes in brightness. All these TV systems use this presumption and only transmit chroma In bright light the eye is more sensitive to colour information and in dim light it can't see colour at all and relies on peripheral black and white vision. That's why you are more likely to see dim stars by not looking at them directly but to the side. Quite true, but this isn't the point I was trying to make. On top of that if two colours are placed next to each other the brain will merge them into another colour if you are looking from far away. Which is another way of saying that visual acuity is less for colour changes than for brightness changes, which *is* the point I was trying to make. Rod. |
The message
from "Agamemnon" contains these words: "Roderick Stewart" wrote in message om... In article , Ben wrote: No one (I think) really addressed the 3rd question regarding colour resolution. Perhaps, like me, people did not really understand the question. I think the OP was referring to the fact that in PAL the vertical chrominance resolution is only half that of the luminance resolution. Digital doesn't do that sort of thing. People who think this is important don't understand the question. All the analogue colour encoding systems have less than half the horizontal chrominance resolution anyway, because that's all that's required, so reducing the vertical resolution to match will do no harm at all. All these systems are designed to take account of the way the human visual system works and not waste bandwidth by transmitting information that nobody will see. Yes, quite true most of the time. That's not to say a matching colour resolution wouldn't improve the percieved quality on static or nearly static images. Even so, the colour component bandwidth costs in analogue transmission systems just don't justify the relatively small improvement this would make, even considering static scenes. The human visual system does not work like that at all either at close range or in bright light. The centre of your field of view is more densely packed with colour receptors than B/W and because of this it provides the highest resolution image and that's what gives you the ability to read. If what you are saying was done on a computer display it would be completely intolerable. Its bad enough trying to read coloured text on a dark background as it is. If a system were not designed with 1:1 colour to pixel mapping I would not accept it to be Hi-Dfeinition. In fact I would prefer as 625 line with 1:1 mapping to any 1050 or 720 line system without it. If you compare a 768x576 DVD screen capture with a scanned image from a magazine or digital camera the difference in quality is astonishing. The most legible type is black against a *white* background, ie maximum contrast. The colour resolution of the human eye is lower than that due to luminence differences alone under any lighting conditions. In moving images, the eye can't percieve the same detail as in a static image which is why broadcast TV looks so acceptable most of the time despite it's abysmal standard of resolution compared to even a small computer display (say 800 by 600 pixels). Digital transmission methods can potentially be used, in conjunction with computer grade monitors, to give fast action/low resolution, with high detail on static/slow action scenes which would be a better match to the way human visual perception actually works. The bandwidth requirements would remain constant in that rapid changes require less data per frame but higher frame rate whilst slow/static scenes would use higher data( which would include full colour resolution on very slow/static scenes) per frame at slower frame rate. HTH -- Regards, John. To reply directly, please remove "buttplug" .Mail via the "Reply Direct" button and Spam-bots will be rejected. |
The message
from "Agamemnon" contains these words: "Roderick Stewart" wrote in message om... In article , Agamemnon wrote: People who think this is important don't understand the question. All the analogue colour encoding systems have less than half the horizontal chrominance resolution anyway, because that's all that's required, so reducing the vertical resolution to match will do no harm at all. All these systems are designed to take account of the way the human visual system works and not waste bandwidth by transmitting information that nobody will see. All perfectly true except for those people who compare a TV set to a computer based display system designed to show high resolution images of static images, usually text as well as the ability to display moving images and forget that the primary function of a TV set is to show *moving* images rather than a high resolution image of fine print. The human visual system does not work like that at all either at close range or in bright light. The centre of your field of view is more densely packed with colour receptors than B/W and because of this it provides the highest resolution image and that's what gives you the ability to read. Concentration of receptor cells is irrelevant. I was talking about what the eye perceives. Choice of chrominance bandwidth for NTSC, PAL and SECAM colour What the eye perceives is down to the concentration of receptor cells. But it's still contrast rather than colour differences that provides the most detail. systems, i.e all the main broadcast systems, was based on research that showed that visual acuity is less for changes in colour than for changes in brightness. All these TV systems use this presumption and only transmit chroma In bright light the eye is more sensitive to colour information and in dim light it can't see colour at all and relies on peripheral black and white vision. That's why you are more likely to see dim stars by not looking at them directly but to the side. On top of that if two colours are placed next to each other the brain will merge them into another colour if you are looking from far away. with about one third of the bandwidth used for luminance and they all work. At the intended viewing distance you can't see that the colour iunformation is less sharp. Well, that does tend to break down a little under certain conditions such as when zooming out from a snooker table with red balls on a green cloth slowly turning brown. In this case, we have a largely static scene filled with objects that are familiar to the viewer. The viewer's visual cortex then has the luxury of time to process the (lack of) detail and for the owner of said visual cortex to spot the change of colour with respect to previous experiences of directly viewed snooker tables and red balls on green cloths. The fact that they would have also observed a similar change of colour when directly viewing such scenes of snooker tables at longer distances tends to be forgotten. To be fair, this 'forgetfulness' is more to do with the importance of remembering 'truths' rather than spurious effects due to the limitations of our visual sense. For the most part. the reduced colour resolution nicely matches our visual perception and would not be a distraction. If you wish to invoke intended viewing distance then going by what you have just said at this distance you cant see the difference between normal definition TV and high definition TV either so why bother with high defintion TV, since if as you claim you can only perceive 293 pixels of colour on a 768 column display then doubling that to 768 pixels on a 1572 column display will have no noticeable effect on effect the colour or even the intensity definition either. The eye uses contrast to pick out detail, chroma differences at identical luminence levels are percieved at lower resolution. The analogue transmission systems rely on this limitation of visual perception to save on bandwidth with regard to colour information. Obviously the fact that people are developing high definition TV shows that the difference is noticeable which more or less proves that the so-called research into colour perception you are referring to is a load of baloney even at the intended viewing distance. HDTV is a more visually satisfying experience, especially when dealing with largely static scenes but for scenes with rapid changes it becomes largely wasted on the eye/visual cortex system that is our sense of sight. Analogue transmission of our current 625 PAL standard is wasteful enough of bandwidth just as it is since most of the time it is involved in repeatedly transmitting the same information over and over at 25 frames a second (50 fields a second). HDTV is now only becoming feasable due to the emergence of more intelligent digital transmission techniques which can remove most of the redundency inherent in analogue transmission systems. As far as I am concerned the intended viewing distance is me sitting right in front of my monitor and I can read colour text at 1600x1200 resolution well enough and I can see the individual colours and I can see the blurring caused by halving the colour resolution perfectly well and I can't stand it. I'd prefer a lower screen resolution without any compromise to the colour bandwidth than a higher screen resolution with the colour bandwidth halved. That applies to all of us but you seem to forget that you are dealing with a *static* scene. If you could run a program that jiggled that text about, you'd need to increase the point size in order to be able to read it again. How much you'd need to increase the point size depends on how much 'jiggle' is being applied. Obviously, the more the jiggle. the greater the increase in point size to restore legibility. Don't forget, the sensation of sight is a combination of the eye and the visual cortex which processes the stimuli. The processing function has a bandwidth limit which optimises between processing detail in largely static scenes and processing movement at the sacrifice of detail when the scene is one with rapid temporal changes. A digital system can take full advantage of this and go beyond the simple analogue methods of tailoring the colour content to match the eye's reduced acuity in this area of perception. A properly designed HDTV system could give you the resolution you crave for in static scenes and drop the resolution down to the standard of the current analogue 625 PAL for rapid action content without you noticing the loss. Since TV broadcasting is largely to do with *moving* images, the lack of detail only becomes apparent on those relatively few occasions that involve static scenes which tend to be relatively short lived and involve close ups when text or hand writing needs to be legible. The analogue system meets our visual needs very nicely when it comes to movement but is somewhat lacking in satisfying our need for detail in static scenes. To satisfy that demand using analogue techniques is simply far too wasteful of transmission bandwidth and hence, impractical. Digital methods of transmission will allow both needs to be met with less consumption of bandwidth. HTH -- Regards, John. To reply directly, please remove "buttplug" .Mail via the "Reply Direct" button and Spam-bots will be rejected. |
"Aztech" wrote in message ... "Agamemnon" wrote in message news:419a4fa8$0 [snip] If I also did another experiments and compressed the both the saturation and the hue by the same amount the recombined image shows noticeable shimmering at the edges of objects but its not as bad as the stuff I have watched on DVD which on my PC which is completely blurred compared to scans and digital camera photos at the same resolution. Even a full screen facial portrait looks blurred. Is something else other than the colour being compressed and if so by how much ? Is dynamic range compression being applied to the colour or luminance or saturation. How may bits per pixel are being used. 24-bit colour space. True for MPEG2 4:2:0/4:2:2 distribution (and most other compression schemes I think), though production kit may well use 30bit (10 bit Y, Cr, Cb is sometimes used in production environments, and 12 bits plus if film DI stuff is being done in the HD spatial domain) Steve |
"Agamemnon" wrote in message ... 1) Are Hi-Definition DVD's available and if so can I play them on my DVD Re-Writer with my present hardware and software ? There is no consumer standard for High Definition DVDs as such yet. BluRay (not quite the same as DVD) consumer recorders are available in Japan to record off-air digital HDTV broadcasts - they can store about 25Gb on a single layer disc (with around 48Gb on a double layer one I believe) There is a proposed HD-DVD standard - but I don't think it has launched yet. Microsoft have released some Windows Media 9 HD material on DVD-ROM - but this is not a formal standard. In the case of Terminator 2 (the most mainstream release) it is heavily DRMed - and requires internet connection to be verified as coming from a US IP address (most well known proxy servers won't work apparently) AIUI it is possible that a number of codecs may be supported. MPEG2 (as currently used OTA - and thus also used by the BluRay recorders on sale in Japan - which like the HDTV DVHS recorders sold in the US - record the off-air data without decompressing and recompressing), Windows Media 9, and MPEG4 (H264 ?) are all likely candidates (and more than one may be supported) The DVB (broadcast rather than DVD but obviously these things are linked these days) organisation has just added H264 AVC to MPEG2 as a DVB video codec I believe. 2) Does the system use Anamophic Windscreen or true Windscreen ? Most HDTV schemes proposed use square pixels, 1920x1080 and 1280x720 are the two 16:9 HD sampling schemes used for production. Many MPEG2 HD broadcasts currently on-air in the US, Japan, and HD1 in Europe, broadcast stuff with these sampling structures as well. Australia has chosen to use anamorphic 1440x1080 for transmission (though production is still 1920x1080) to reduce bandwith requirements (it is still pretty much twice the horizontal and vertical resolution of 16:9 anamorphic standard definition at 720x480/476) AIUI some US satellite re-broadcasters are also reducing the horizontal resolution - though not sure if they do this by filtering (and still broadcast at 1920 - just with less HF information present), or by subsamping (and broadcasting at 1440 or lower) I would expect any imminent HD DVD format to support 1920x1080 and 1280x720 as the main sampling structures. They may also support other schemes. 3) Is the colour of the same resolution as the luminance or is it half the resolution or worse like PAL ? I suspect that 4:2:0 sampling will continue to be used - as it has equal horizontal and vertical chroma resolution (4:2:2 has higher vertical resolution than horizontal - though this has advantages during production) I very much doubt a full-bandwith RGB or YCrCb system will be used for a domestic format - for standard video, at normal viewing distances, the eye/brain really doesn't see as much chroma information as luminance. There is loads of research backing up the choice of YCrCb/YUV/YIQ transmission schemes used - which give more bandwith to luminance than chrominance - this dates back to the launch of colour TV transmission in the 50s (with NTSC), and continues through PAL, MAC and MPEG2. 4:2:0 is better than PAL analogue, and much better than NTSC analogue, in chroma bandwith terms - so there is still a significant chroma improvement. It really isn't possible to justify moving from a 12 bit system (1xCr and 1xCb sample for every 4xY samples) to a 24 bit system (1xCr and 1xCb system for every 1xY sample)- doubling the bandwith of the video signal you need to compress, when the improvements are so marginal. If you didn't increase the bandwith you'd be massively increasing the compression, adding huge amounts of artefacts to the system I would expect H264 and Windows Media 9 to both continue with 4:2:0 chroma subsampling. (In fact some HDTV format VTRs - like the non-SR HDCam format- I believe, use 4:1:1 sampling, as does miniDV in 525/60 territories, as well as DVCPro in all territories) Steve |
| All times are GMT +1. The time now is 04:13 AM. |
Powered by vBulletin® Version 3.6.4
Copyright ©2000 - 2021, Jelsoft Enterprises Ltd.
HomeCinemaBanter.com