HDTV with good resolution?

Discussion in 'Displays' started by JoshR, Jun 20, 2004.

  1. JoshR

    JoshR Agent

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    Well, it looks like I may be making the jump to HDTV in the coming months. I'll have a budget of $1,000 or so, and it's for the living room and I'll want at least 30", so it'll most likely be a CRT. Suggestions are welcome, and I have my eye on a new Panasonic coming out in the near future. But here's why I'm really posting:

    While looking at various specs, I've noticed that no TV on the market today comes close to displaying the full 1080i HDTV signal. Even 42" flat panels have, on average, about half of the total resolution HDTV is capable of. For example, the Panasonic TH42PX25U 42" plasma has a native resolution of 1024x768. That's a vertical resolution of 768 lines(with 768 pixels per column), meaning, perfectly good for 720p HDTV.

    So, my first question: any clue when we'll sets capable of 1080i? People often cite the 4x greater resolution of HDTV, but that's only true with 1080i. 720p gives you about 2x better resolution than NTSC would, plus progressive scan, which is of secondary importance to me. I'm all about the pixels. [​IMG] When are the "real" HDTV sets coming out? Will it be another 5 years? Should I wait?

    My second question is about that particular panasonic. Most 16:9 sets have resolutions like 1280x720, or 1366x768, both of which are 16:9 resolutions that would handle 720p nicely. Anyone know why this Panasonic would have a 4:3 native resolution when it's a 16:9 screen? I thought that was strange.
     
  2. JoshR

    JoshR Agent

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    Well, it looks like I may be making the jump to HDTV in the coming months. I'll have a budget of $1,000 or so, and it's for the living room and I'll want at least 30", so it'll most likely be a CRT. Suggestions are welcome, and I have my eye on a new Panasonic coming out in the near future. But here's why I'm really posting:

    While looking at various specs, I've noticed that no TV on the market today comes close to displaying the full 1080i HDTV signal. Even 42" flat panels have, on average, about half of the total resolution HDTV is capable of. For example, the Panasonic TH42PX25U 42" plasma has a native resolution of 1024x768. That's a vertical resolution of 768 lines(with 768 pixels per column), meaning, perfectly good for 720p HDTV.

    So, my first question: any clue when we'll sets capable of 1080i? People often cite the 4x greater resolution of HDTV, but that's only true with 1080i. 720p gives you about 2x better resolution than NTSC would, plus progressive scan, which is of secondary importance to me. I'm all about the pixels. [​IMG] When are the "real" HDTV sets coming out? Will it be another 5 years? Should I wait?

    My second question is about that particular panasonic. Most 16:9 sets have resolutions like 1280x720, or 1366x768, both of which are 16:9 resolutions that would handle 720p nicely. Anyone know why this Panasonic would have a 4:3 native resolution when it's a 16:9 screen? I thought that was strange.
     
  3. ChrisWiggles

    ChrisWiggles Producer

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    Josh: First, you have to understand the difference between "displaying" and resolving, especially since you intend to get a CRT. Fixed pixel devices, say a DLP or LCD projection unit have, as you can guess, a fixed number of pixel elements on their panels, and that is exactly how many pixels they can display and resolve.

    CRTs work totally differently, especially projection-CRTs. With a CRT-based projection unit (RPTV or front-projection) you can usually easily display 1080i, however, whether or not that is properly resolved varies. The resolving capabilities with a CRT projection setup have to do with the physical size of the electron beam as it scans the phosphors on the tube. If you want 1080 lines, you need to be able to scan that many lines on the tubeface without jamming them too many too close together and overlapping. To properly do 1080i, you need the capability to resolve 1080p, which few CRTs, except high-end 9-inch models that are setup well, are capable of.

    As for displays that can properly do a full 1080p, you are limited at this point to pretty much high-end 9-inch CRT projection units, or the Sony Qualia, or the JVC, which both have native 1080p panel resolutions. But we are at priceranges that are way beyond where you are, so the answer is pretty much no, you can't expect, even, IMO, in the near future, to see full 1080p capable displays at a $1K pricerange. And I wouldn't really worry about it anyway, since most of your viewing is probably DVD, and here, the DVD is largely your limiting factor of quality, and you don't need to get full 1080p to blow way past DVD.

    Also, resolution is not the only story when it comes to PQ, there are many many other factors, don't get tied to what the resolving capabilities are only.
     
  4. ChrisWiggles

    ChrisWiggles Producer

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    Josh: First, you have to understand the difference between "displaying" and resolving, especially since you intend to get a CRT. Fixed pixel devices, say a DLP or LCD projection unit have, as you can guess, a fixed number of pixel elements on their panels, and that is exactly how many pixels they can display and resolve.

    CRTs work totally differently, especially projection-CRTs. With a CRT-based projection unit (RPTV or front-projection) you can usually easily display 1080i, however, whether or not that is properly resolved varies. The resolving capabilities with a CRT projection setup have to do with the physical size of the electron beam as it scans the phosphors on the tube. If you want 1080 lines, you need to be able to scan that many lines on the tubeface without jamming them too many too close together and overlapping. To properly do 1080i, you need the capability to resolve 1080p, which few CRTs, except high-end 9-inch models that are setup well, are capable of.

    As for displays that can properly do a full 1080p, you are limited at this point to pretty much high-end 9-inch CRT projection units, or the Sony Qualia, or the JVC, which both have native 1080p panel resolutions. But we are at priceranges that are way beyond where you are, so the answer is pretty much no, you can't expect, even, IMO, in the near future, to see full 1080p capable displays at a $1K pricerange. And I wouldn't really worry about it anyway, since most of your viewing is probably DVD, and here, the DVD is largely your limiting factor of quality, and you don't need to get full 1080p to blow way past DVD.

    Also, resolution is not the only story when it comes to PQ, there are many many other factors, don't get tied to what the resolving capabilities are only.
     
  5. Adam.Heckman

    Adam.Heckman Second Unit

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    Josh, you say you want a crt? I assumed, unlike Chris, that you wanted a direct view. Much like my Philips 30pw850h.

    As far as I know (I'm not an expert) my set can display 1080i. Along with 480. It also scales 720 up, but only decently. I am under the impression that just about all direct view CRTs are fully capapble of 1080i, and there are many on the market.

    Could I please have some clarification on this, chris? Thanks.
     
  6. Adam.Heckman

    Adam.Heckman Second Unit

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    Josh, you say you want a crt? I assumed, unlike Chris, that you wanted a direct view. Much like my Philips 30pw850h.

    As far as I know (I'm not an expert) my set can display 1080i. Along with 480. It also scales 720 up, but only decently. I am under the impression that just about all direct view CRTs are fully capapble of 1080i, and there are many on the market.

    Could I please have some clarification on this, chris? Thanks.
     
  7. ChrisWiggles

    ChrisWiggles Producer

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    I don't follow direct-views that much (at all really...) but they do have somewhat fixed capabilities of resolution due to their shadow mask, or trinitron lines. Yes many are capable of displaying 1080i, the kickers is whether that is being properly resolved. Since I don't follow direct views, I really don't know... but 1080i is quite difficult to resolve properly, since technically you need 1080p resolving capabilities to do it correctly.
     
  8. ChrisWiggles

    ChrisWiggles Producer

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    I don't follow direct-views that much (at all really...) but they do have somewhat fixed capabilities of resolution due to their shadow mask, or trinitron lines. Yes many are capable of displaying 1080i, the kickers is whether that is being properly resolved. Since I don't follow direct views, I really don't know... but 1080i is quite difficult to resolve properly, since technically you need 1080p resolving capabilities to do it correctly.
     
  9. Adam.Heckman

    Adam.Heckman Second Unit

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    Thanks Chris, this is interesting. I have one more question if I can...
    Why must a set have to resolve 1080p in order to properly display 1080i? As far as I know, there are few if any sets that make use of 1080p.
    Thanks again.
     
  10. Adam.Heckman

    Adam.Heckman Second Unit

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    Thanks Chris, this is interesting. I have one more question if I can...
    Why must a set have to resolve 1080p in order to properly display 1080i? As far as I know, there are few if any sets that make use of 1080p.
    Thanks again.
     
  11. JoshR

    JoshR Agent

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    Yes, I'm looking for a direct-view tube TV, not a rear projection.

    So, let's see if I understand this: "display" means how many pixels the electron gun can paint on the back of the glass, and since that's an analog process, the answer is technically an infinite number. But practically, to see those dots requires a shadow grill(or something similar) which provides a hardware limitation and affects how the viewer will see those dots. And we call that "resolving".

    Ok. [​IMG]

    So let me put it like this: The biggest point of HDTV, according to a multitude of sources, is that it's capable of 4 times as much resolution as NTSC. But that requires a 1080i signal, and a TV that can display it. I don't think any direct views like this exist, but if they do, I've love to hear about them. If anyone has an idea when they'll start making them this way, I'd like to know about that as well. I've looked all over the web and there's no clearcut info on this.

    Here's the logic I'm using, if anyone cares. With a 16:9 ratio, 1080 horizonally means 1920 vertical lines. And that would be 4 times as much resolution as a regular TV. Put another way, 1920x1080 = 2073600 pixels. NTCS resolution is, at the very best, 525 scanlines, at a 4:3 ration, that means 525*700, which is 367408. About 1/4. And Im counting non-visible lines because I'm figuring something similar happens with HDTV.

    720p, on the other hand, with 720 horizontal lines and around 1280 vertical lines, is 921600. Less than half of the resolution HDTV is capable of.

    So, when will we get signals that take full advantage of HDTV, and when will they make TVs that can show it?
     
  12. JoshR

    JoshR Agent

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    Yes, I'm looking for a direct-view tube TV, not a rear projection.

    So, let's see if I understand this: "display" means how many pixels the electron gun can paint on the back of the glass, and since that's an analog process, the answer is technically an infinite number. But practically, to see those dots requires a shadow grill(or something similar) which provides a hardware limitation and affects how the viewer will see those dots. And we call that "resolving".

    Ok. [​IMG]

    So let me put it like this: The biggest point of HDTV, according to a multitude of sources, is that it's capable of 4 times as much resolution as NTSC. But that requires a 1080i signal, and a TV that can display it. I don't think any direct views like this exist, but if they do, I've love to hear about them. If anyone has an idea when they'll start making them this way, I'd like to know about that as well. I've looked all over the web and there's no clearcut info on this.

    Here's the logic I'm using, if anyone cares. With a 16:9 ratio, 1080 horizonally means 1920 vertical lines. And that would be 4 times as much resolution as a regular TV. Put another way, 1920x1080 = 2073600 pixels. NTCS resolution is, at the very best, 525 scanlines, at a 4:3 ration, that means 525*700, which is 367408. About 1/4. And Im counting non-visible lines because I'm figuring something similar happens with HDTV.

    720p, on the other hand, with 720 horizontal lines and around 1280 vertical lines, is 921600. Less than half of the resolution HDTV is capable of.

    So, when will we get signals that take full advantage of HDTV, and when will they make TVs that can show it?
     
  13. JoshR

    JoshR Agent

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    I think I can venture an answer to your question, Adam. This "resolving" thing has to do with a fixed piece of hardware...a shadow mask or grille or whatever it is that sits right behind the glass. That's not something that can move with the electron gun; it'll have holes of a certain size and distance to each other, make to guide the beam of light to the glass, creating pixels. It's cut(or maybe they paint or silkscreen it, or laser etch...they're pretty thin) that way from the factory. So even though the gun will only use every other row of that grille in each pass, all the holes must already be cut ahead of time. Which would mean it could resolve progressive scan.

    That's my theory, anyway. This is fun!
     
  14. JoshR

    JoshR Agent

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    I think I can venture an answer to your question, Adam. This "resolving" thing has to do with a fixed piece of hardware...a shadow mask or grille or whatever it is that sits right behind the glass. That's not something that can move with the electron gun; it'll have holes of a certain size and distance to each other, make to guide the beam of light to the glass, creating pixels. It's cut(or maybe they paint or silkscreen it, or laser etch...they're pretty thin) that way from the factory. So even though the gun will only use every other row of that grille in each pass, all the holes must already be cut ahead of time. Which would mean it could resolve progressive scan.

    That's my theory, anyway. This is fun!
     
  15. Allan Jayne

    Allan Jayne Cinematographer

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    I would think that if a TV picture tube can resolve 1080i it will also resolve 1080p, and vice versa.

    Most shadow masks have vertical slits, so the "pitch" of the scan lines can be anything.

    In my opinion the smallest spot resolvable with a shadow mask spans any two color stripes on the screen. In terms of horizontal position, a pixel could also correspond to half of a red stripe, all of the green stripe next to it and half of a blue stripe next to that. In this way the spot will at least be a pastel color as opposed to a deep color if the spot size was only one phosphor stripe's width.

    Video hints:
    http://members.aol.com/ajaynejr/video.htm
     
  16. Allan Jayne

    Allan Jayne Cinematographer

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    I would think that if a TV picture tube can resolve 1080i it will also resolve 1080p, and vice versa.

    Most shadow masks have vertical slits, so the "pitch" of the scan lines can be anything.

    In my opinion the smallest spot resolvable with a shadow mask spans any two color stripes on the screen. In terms of horizontal position, a pixel could also correspond to half of a red stripe, all of the green stripe next to it and half of a blue stripe next to that. In this way the spot will at least be a pastel color as opposed to a deep color if the spot size was only one phosphor stripe's width.

    Video hints:
    http://members.aol.com/ajaynejr/video.htm
     
  17. ChrisWiggles

    ChrisWiggles Producer

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    there are a lot of things going on.

    First, there is the electronic capability. Most sets do not have the electronic input capability to even accept a 1080p signal, and this is somewhat irrelevant to being able to properly resolve 1080 (i or p).

    What a set can display, is pretty much what the electronics on a CRT are capable of controlling. Using a projection-CRT example, since this is what I'm most familiar with, you can feed it signals that the electronics are capable of displaying, for instance maybe 480p, 720p, 1080i in an RPTV. It is capable of displaying these resolutions. It probably will not accept 1080p, and does not have the electronic capabilities to attempt to display it.

    What it can RESOLVE, does not hinge on the electronic input capabilities, but rather the set's control of the electron beam, and the setup quality of that beam size. This limits how many lines you can cram onto the phosphor before you begin to overlap. 1080i, to properly resolve, needs 1080 lines resolvable, equivalent to 1080p (but the electronics needed are far less, since we're only drawing half at any one time).

    Why, you ask? 1080i only draws 540 lines in any one pass, so you may think it only needs to be able to resolve 540 lines, since that's all it's drawing at any one pass. However, those lines are supposed to be in different vertical positions, sort of like half-opened venetian blinds. One bass draws 540 lines with spaces between them, the next pass draws 540 lines in those spaces, and repeat. To to properly do 1080i needs 1080p resolving capabilities, which very very few sets can do.

    Mine can take way beyond 1080p in electronic inputs, but I cannot properly resolve 1080p without overlapping the scanlines and softening the image.

    I hope that makes sense.

    This applies to projection CRTs, I'm not exactly sure how this translates to direct-views, since there is also the shadow mask/trinitron line limits which come into play.
     
  18. ChrisWiggles

    ChrisWiggles Producer

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    there are a lot of things going on.

    First, there is the electronic capability. Most sets do not have the electronic input capability to even accept a 1080p signal, and this is somewhat irrelevant to being able to properly resolve 1080 (i or p).

    What a set can display, is pretty much what the electronics on a CRT are capable of controlling. Using a projection-CRT example, since this is what I'm most familiar with, you can feed it signals that the electronics are capable of displaying, for instance maybe 480p, 720p, 1080i in an RPTV. It is capable of displaying these resolutions. It probably will not accept 1080p, and does not have the electronic capabilities to attempt to display it.

    What it can RESOLVE, does not hinge on the electronic input capabilities, but rather the set's control of the electron beam, and the setup quality of that beam size. This limits how many lines you can cram onto the phosphor before you begin to overlap. 1080i, to properly resolve, needs 1080 lines resolvable, equivalent to 1080p (but the electronics needed are far less, since we're only drawing half at any one time).

    Why, you ask? 1080i only draws 540 lines in any one pass, so you may think it only needs to be able to resolve 540 lines, since that's all it's drawing at any one pass. However, those lines are supposed to be in different vertical positions, sort of like half-opened venetian blinds. One bass draws 540 lines with spaces between them, the next pass draws 540 lines in those spaces, and repeat. To to properly do 1080i needs 1080p resolving capabilities, which very very few sets can do.

    Mine can take way beyond 1080p in electronic inputs, but I cannot properly resolve 1080p without overlapping the scanlines and softening the image.

    I hope that makes sense.

    This applies to projection CRTs, I'm not exactly sure how this translates to direct-views, since there is also the shadow mask/trinitron line limits which come into play.
     
  19. Steve Schaffer

    Steve Schaffer Producer

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    it's been my understanding that on crt based displays, resolution pretty much refers to how many individual vertical lines (think picket fence) the set can display, not how many scanlines (these run horizontally, not vertically) are used to "draw the picture".

    Any set labelled as HD-capable must be able to draw either 1080 interlaced scan lines or 720 progressive scanlines for a crt, or have at least 1080 or 720 rows of pixels from top to bottom (I think).

    Any crt based HD ready set can do the 1080i scanlines, the variation comes in how many "picket fence posts" it can display and this is where the shadow mask or trinitron wire grid can become a limiting factor. Sony's top line XBR 34" direct view is the best of it's type by a pretty decent margin but is a good bit more than $1000.

    rptvs use 3 separate crts instead of one-red, green, and blue. Since the purpose of the shadow mask in a direct view set is to prevent the electron beam from straying to the wrong color phosphor (the tube has all three colors on a single tube) the crts in an rptv don't require shadow masks or trinitron grids and thus can theoretically resolve more vertical lines than most direct view sets.

    Most rptvs use 7 inch tubes which still won't quite do the full number of pixels spec'd for HD, but still come closer to doing so than a direct crt set. A very few uber-expensive crt based rptvs with 9 inch tubes can do the whole enchilada, but the cost to performance benifit isn't that great for most of us common folk.

    Basically in the 1k range you will probably get better resolution with a $1300 or so 42 to 48 inch crt based rptv than with a sub 2k direct view. There are of course other considerations like off-angle viewing and resistance to burn in that need to be taken into account.
     
  20. Steve Schaffer

    Steve Schaffer Producer

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    it's been my understanding that on crt based displays, resolution pretty much refers to how many individual vertical lines (think picket fence) the set can display, not how many scanlines (these run horizontally, not vertically) are used to "draw the picture".

    Any set labelled as HD-capable must be able to draw either 1080 interlaced scan lines or 720 progressive scanlines for a crt, or have at least 1080 or 720 rows of pixels from top to bottom (I think).

    Any crt based HD ready set can do the 1080i scanlines, the variation comes in how many "picket fence posts" it can display and this is where the shadow mask or trinitron wire grid can become a limiting factor. Sony's top line XBR 34" direct view is the best of it's type by a pretty decent margin but is a good bit more than $1000.

    rptvs use 3 separate crts instead of one-red, green, and blue. Since the purpose of the shadow mask in a direct view set is to prevent the electron beam from straying to the wrong color phosphor (the tube has all three colors on a single tube) the crts in an rptv don't require shadow masks or trinitron grids and thus can theoretically resolve more vertical lines than most direct view sets.

    Most rptvs use 7 inch tubes which still won't quite do the full number of pixels spec'd for HD, but still come closer to doing so than a direct crt set. A very few uber-expensive crt based rptvs with 9 inch tubes can do the whole enchilada, but the cost to performance benifit isn't that great for most of us common folk.

    Basically in the 1k range you will probably get better resolution with a $1300 or so 42 to 48 inch crt based rptv than with a sub 2k direct view. There are of course other considerations like off-angle viewing and resistance to burn in that need to be taken into account.
     

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