Samsung LED TV

[PeterCH]

Actually higher than the best Plasma. Plasma cells do retain some charge even when "off". OLED is pure black. OLED also use very little power. Main issue with OLED is cost and lifespan. Expect to see some 30" models on the market this year with a very high pricetag.

Great summary-- thanks.

Maybe better on paper, but the latest generation of Pioneer Kuro range
have subjectively 'perfect' contrast. Read up the reviews on EngagetHD,
when they turned the plasma on in an almost perfect dark press room,
the audience was awed by the perfect white on perfect black. In fact the instruments EngagetHD used to measure the contrast went off-scale - they
couldn't reliably measure contrast further, it was so high - something like 1:30,000 or better - the paper figures of 'dynamic' 1:50:000 etc are all made up and can't even be measured in practical scenarios.

Once you get over a certain level the human eye or rather the human sensory cortex fails to perceive further differences. We judge differences on a logarithmic scale hence you can tell that 1000g is heavier than 500g but you can't tell that 11kg is heavier than 10kg, this applies to perception of sound, vision and other senses.

In addition, the use of LEDs allows for blackframe interpolation to enhance the 100Hz motion adaption of the set. This visibly reduces the appearance of LCD ghosting.

Isn't Ghosting a pixel switching problem? What the 100MHz motion feature in LCD TVs does is fill in additional frames to prevent motion stuttering (happens during fast pans for example, hence the reason sports broadcasts use 1080i not 720p),
this is more of a source signal problem too. Fast motion 1080p video will suffer from this problem as it's only 30p, 24p, or 25p. On the other hand 1080i50 or 1080i60 will appear smoother although lacking spatial resolution.
It may be that current LCD sets - pre 100Mhz or 120Mhz motion do not display these even smoothly enough.

Ghosting occurs in slow pixel response displays. I don't see how a different colour gamut backlight can diminish that. Coincidentally the more expensive and better the display the more likely it will have ghosting - as S-IPS/PVA/MVA/ASV based LCD have slower pixel on/off switching than TN based LCD.
TN has a lower colour representation though.

The Samsung LED LCDs use side-based LED lighting. i.e. In order to make the TV thinner, the lighting electronics are moved from behind the LCD to the edge of the screen. Cosmetically it is a great idea (this is the way most notebook LCD screens are lit), as the TV looks thin and modern. But functionally it has some drawbacks. Notebook screens are fairly small and getting an even coverage of light is not so problematic. But on a 40" or larger screen it gets very difficult to get even backlighting, and the Samsung sets suffer from this quite badly. Also, the advantage of selective LED tuning to enhance contrast and colour is nullified because the LEDS don't correspond to a certain portion of the screen. Lastly, as far as I am aware (and I could be wrong on this), Samsung is using white LEDs. These LEDs do not cover the same colour gamut that is possible using component colour LEDs (RGB).

Extended gamut CCFL as in my 30 inch Dell allows for almost LED like color gamut - in fact the most recent Dell has 107% NTSC color gamut. HP and others have employed these backlights too, while NEC, LaCie amd Iliyama don't even use them but standard CCFL, or maybe have recently started to use them. Backlight is secondary to LCD technology employed, a TN based LED b/l display will suck compared to an S-IPS CCFL one.

 

[arf9999]

Great summary-- thanks.

Maybe better on paper, but the latest generation of Pioneer Kuro range
have subjectively 'perfect' contrast. Read up the reviews on EngagetHD,
when they turned the plasma on in an almost perfect dark press room,
the audience was awed by the perfect white on perfect black. In fact the instruments EngagetHD used to measure the contrast went off-scale - they
couldn't reliably measure contrast further, it was so high - something like 1:30,000 or better - the paper figures of 'dynamic' 1:50:000 etc are all made up and can't even be measured in practical scenarios.

True. But I'm a geek.. on paper OLED offers more than 1,000,000:1 contrast ratio

Once you get over a certain level the human eye or rather the human sensory cortex fails to perceive further differences. We judge differences on a logarithmic scale hence you can tell that 1000g is heavier than 500g but you can't tell that 11kg is heavier than 10kg, this applies to perception of sound, vision and other senses.

agree 100%. Just for reference: Films shown at cinemas typically only offer 500:1 contrast ratio.

Isn't Ghosting a pixel switching problem?

yes.

What the 100MHz motion feature in LCD TVs does is fill in additional frames to prevent motion stuttering (happens during fast pans for example, hence the reason sports broadcasts use 1080i not 720p),
this is more of a source signal problem too. Fast motion 1080p video will suffer from this problem as it's only 30p, 24p, or 25p. On the other hand 1080i50 or 1080i60 will appear smoother although lacking spatial resolution.
It may be that current LCD sets - pre 100Mhz or 120Mhz motion do not display these even smoothly enough.

Firstly. Hertz, not MegaHertz.
One of the issues with LCD is slower pixel switching, and motion blur and ghosting are the result. This can be reduced somewhat with faster panels, and again by increasing the refresh rate (50Hz - 100Hz - 200Hz) and by interpolating intermediate frames. However this is not always successful due to persistence of vision. So by using the ability of the LEDs to switch on and off instantly, an additional black frame can be inserted. This means that the persistence of vision is overcome to an extent.
So instead of 50p being Frame A and then Frame B; the result for a 100Hz model will be A1;Black;A1+B1 interpolated; Black; B1; B1+A2;Black;A2; etc...

I don't see how a different colour gamut backlight can diminish that.

Nothing to do with Gamut.

Coincidentally the more expensive and better the display the more likely it will have ghosting - as S-IPS/PVA/MVA/ASV based LCD have slower pixel on/off switching than TN based LCD.
TN has a lower colour representation though.

the Sony and Samsung panels are PVA.

Extended gamut CCFL as in my 30 inch Dell allows for almost LED like color gamut - in fact the most recent Dell has 107% NTSC color gamut. HP and others have employed these backlights too, while NEC, LaCie amd Iliyama don't even use them but standard CCFL, or maybe have recently started to use them. Backlight is secondary to LCD technology employed, a TN based LED b/l display will suck compared to an S-IPS CCFL one.

True. However using RGB LEDs offers a wider gamut than CCFL at the moment, even the wide gamut CCFL that is available (but again it is a slight difference). That said, white LEDs have a lower gamut than Wide gamut CCFL. Again making a bit of a mockery of the Samsung advertising... Series 6 will have better gamut than 7 or 8.

 

[PeterCH]

True. But I'm a geek.. on paper OLED offers more than 1,000,000:1 contrast ratio

Which can't even be measured by instruments in practice.

agree 100%. Just for reference: Films shown at cinemas typically only offer 500:1 contrast ratio.

Must be because of them being projector driven, I gather.

So instead of 50p being Frame A and then Frame B; the result for a 100Hz model will be A1;Black;A1+B1 interpolated; Black; B1; B1+A2;Black;A2; etc...

You mean 50i, there is no 1080p50, there's only 1080i50. Progressive HD comes in 24, 25 and 30 frames per second. The 50 or 60 are interlaced fields.

Nothing to do with Gamut.

Ok you mentioned the additional black field being inserted. Surely, if you're still
showing 25 fps progressive video in a PAL region, your pixel still needs to switch on/off 25 times per second though, or 30 for NTSC regions. Still required the actual LCD to be up to scratch and not its backlight.

the Sony and Samsung panels are PVA.

Which is still slower than TN when it comes to pixel on/off switching. Hence most gamer PC screens are TN but are bad for photo/video colour correction and have colour banding issues when displaying certain gradients.

 

[arf9999]

You mean 50i, there is no 1080p50, there's only 1080i50. Progressive HD comes in 24, 25 and 30 frames per second. The 50 or 60 are interlaced fields.

Of course there is 1080p50 and 60! Not broadcast, and unlikely to be used, but it exists. In any case I was merely showing an example. Multichoice HD channel is 720p50.

Ok you mentioned the additional black field being inserted. Surely, if you're still showing 25 fps progressive video in a PAL region, your pixel still needs to switch on/off 25 times per second though, or 30 for NTSC regions. Still required the actual LCD to be up to scratch and not its backlight.

Actually the pixel theoretically needs to switch 100 times per second. Most panels can't refresh this fast, but by adding the black frame (from the backlight - not the panel) the visible ghosting artefacts (both real - LCD pixel refresh; and virtual - human brain's persistence of vision) are reduced.

Which is still slower than TN when it comes to pixel on/off switching. Hence most gamer PC screens are TN but are bad for photo/video colour correction and have colour banding issues when displaying certain gradients.

Yup. Which is why you shouldn't buy a panel based on refresh speed unless you don't mind incorrect colour.

 

[PeterCH]

Of course there is 1080p50 and 60! Not broadcast, and unlikely to be used, but it exists. In any case I was merely showing an example. Multichoice HD channel is 720p50.

The ATSC spec does not even allow for 1080p60. Oh sure you can get 4K, 6K, 8K and even higher formats, but it's the same thing - such a format is more or less a theoretical format. Bluray video is 1080p24. Capture becomes difficult at higher rates (60p is 200Mb/sec) and you can forget about broadcast. Most broadcast HD is 1080i60 or 720p60/50. Then much HD video is captured on pixel shift - the BBC Planet Earth documentary was captured on a Panasonic Varicam HD which has 1Mp sensors (1,019,280 pixels) - not full 1920by1080 - so you're not even seeing proper 2Mp frames. Many HD productions are captured on HDV - 1440 by 1080. Even many HD cams as above use pixel shift to generate 1920 by 1080.

The current formats used (and recordable on cameras) are 1080p24, 1080p30 and 1080p25 (PAL) as well as 1080i60/50. 720p50 (PAL) and 720p60
(NTSC) are also available, as you said. Film transfer as you know goes straight to 1080p24.

These are the also the formats one can edit in Avid Media Composer, Premiere and FCS.

For all practical purposes video 1080p60 is not a format to consider at this stage as it can neither be broadcast nor played back on any mainstream hardware (the only possible exception are graphics output by the PS3, but video played back is bastardised 24p)
so it makes no sense to use it as a mainstream example, after all one can say - Ultra High Definition is possible and Red cameras can shoot in upto 12K
(red.com has more info).

I'm not aware of any format I could purchase a 1080p60/50 movie on - nor download it.

Actually the pixel theoretically needs to switch 100 times per second. Most panels can't refresh this fast, but by adding the black frame (from the backlight - not the panel) the visible ghosting artefacts (both real - LCD pixel refresh; and virtual - human brain's persistence of vision) are reduced.

Oh ok, that makes sense, to mask the effects of smearing.

Yup. Which is why you shouldn't buy a panel based on refresh speed unless you don't mind incorrect colour.

Sadly virtually all consumer displays are like this.

 

[arf9999]

The ATSC spec does not even allow for 1080p60. Oh sure you can get 4K, 6K, 8K and even higher formats, but it's the same thing - such a format is more or less a theoretical format. Bluray video is 1080p24. Capture becomes difficult at higher rates (60p is 200Mb/sec) and you can forget about broadcast. Most broadcast HD is 1080i60 or 720p60/50. Then much HD video is captured on pixel shift - the BBC Planet Earth documentary was captured on a Panasonic Varicam HD which has 1Mp sensors (1,019,280 pixels) - not full 1920by1080 - so you're not even seeing proper 2Mp frames. Many HD productions are captured on HDV - 1440 by 1080. Even many HD cams as above use pixel shift to generate 1920 by 1080.

Partially true, but the world doesn't end in the USA. There are more and more products available that capture true 2K images. HDCAM SR for example. Also, improvements in compression and processing allow for higher resolution capture and broadcast. Europe (EBU) has already tabled 1080p50/60 standards.

From Wikipedia:

In Europe, 1080p25 signals have been supported by the DVB suite of broadcasting standards; higher frame rates, such as 1080p50 and 1080p60, have been foreseen as the future broadcasting standard, [4] though they require more bandwidth and/or advanced codec such as H.264/MPEG-4 AVC. Starting Fall 2009, ETSI and EBU, the maintainers of DVB, will require that DVB-compatible digital receivers feature support for 1080p signals at 50/60 Hz and MPEG-4 AVC High Profile Level 4.2 with Scalable Video Coding extensions. [7] [8] SVC enables forward compatibility with 1080p50 broadcasting for older MPEG-4 AVC receivers, so they will only recognize baseline SVC stream coded at a lower resolution/frame rate and gracefully ignore additional frames, while newer hardware will be able to decode full-resolution 1080p50 signal. EBU recommends that legacy hardware should at least not crash in presence of SVC or 1080p50 (and higher resolution) signals.[7]

I'm not aware of any format I could purchase a 1080p60/50 movie on - nor download it.

MPEG-4 AVC High Profile Level 4.2 would work


But again... I was showing an example and utilised progressive scanning because it is easier to illustrate the interpolation. As I said there is progressive HD at 50p, it's called 720p50. If I used 1080i to illustrate, I'd have to add all the field to frame de-interlacing and it'd get very ugly and unclear.