or Connect
AVS › AVS Forum › Display Devices › LCD Flat Panel Displays › 120hz LCD vs CRT - pics
New Posts  All Forums:Forum Nav:

120hz LCD vs CRT - pics

post #1 of 196
Thread Starter 
The following is a gaming comparison between the Samsung LN-T4669 120hz LCD and my four-year old CRT monitor.
Most of the issues here affect TV and movie viewing as well.
Samsung's 69 and 71 series are popular and mostly identical except for their screen coatings (79 is glossy).
There is a lot of confusion as to the purpose of 120hz. In-depth reading here and here.

Test set up:

LCD: Samsung LN-T4669 LCD - same as LN-T4671 but with anti-glare
CRT: Dell P1130 trinitron - discontinued
Console: PS3 (1080p/24p)
PC: Nvidia 7900gtx/Intel E6600
Software: Pixperan (disclaimer: read warning), DigitalVideo Essentials (later), games
LCD connections: DVI-VGA (PC), DVI - HDMI (PC), HDMI-HDMI (PS3)
CRT connections: DVI-VGA
All possible TV processing OFF


Samsung LN-T4669 LCD (top)
Dell P1130 Trinitron CRT (bottom)





Viewing angles: Pixperan's gamma test (above) shows darker squares at the sides of the Samsung.
The contrast variation above isn't bad during games but noticeable. More pics below - not bad for a 4yr old heavily used CRT.




Mura (below) is variation in backlight brightness. This was taken with a high ISO number.
In reality it's not seen because human contrast is limited (at least mine).







Pixel Response (below): Frame transitions were captured with a 1/1000 camera shutter showing new frames overlapping old ones on the LCD - old pixels are slow to fade away.
LCDs have improved their response times greatly, so the overlap below didn't last long enough to be seen (by me). Pixel response doesn't seem to be an issue with the Samsung.
The pic below can even be compared with those of the fastest LCDs at Behardware here or here
Samsung probably uses the same "double overdrive" mentioned in BeHardware's review of the 100hz LE4073BD, - the tip-off being a white outline behind the 120hz car.
Other things noticed: The 8ms response time quoted by Samsung seems accurate (else the 120hz pic would have three overlapping images instead of two).
Also, the overlapping cars are 1/2 as far apart in the 120hz pic because for each frame comming from the graphics card, the TV inserts one in-between.








In reality, blur came from a completely unrelated source called the sample-and-hold effect (below). Response time and sample-and-hold are the two (unrelated) causes for LCD blur. Sample-and-hold can only be captured by special cameras.
Below is an accurate simulation of a moving object (showing sample-and-hold blur on the LN-T4669). It was rendered by Pixperan's "streaky picture test"; a free download.







Explanation of sample and hold Blur:

Any time an object moves relative to the eye it will blur. Since the eyes track moving objects smoothly ("smooth pursuit reflex") but TVs display moving objects as a sucession of still snapshots (frames), each snapshot blurs as the eye passes over. The blur occurs in the eye and is not from the screen. CRT images aren't displayed long enough to blur as the eye passes over but LCDs hold images for the entire frame duration (sample-and-hold):

Quote:
All of the newer display technologies such as LCD, plasma, DLP, and so on, have essentially a sample-and-hold characteristic. When a pixel is addressed, it is loaded with a value and stays at that light output value until it is next addressed. From an image portrayal point of view, this is the wrong thing to do. The sample of the original scene is only valid for an instant in time. After that instant, the objects in the scene will have moved to different places. It is not valid to try to hold the images of the objects at a fixed position until the next sample comes along that portrays the object as having instantly jumped to a completely different place. Your eye tracking will be trying to smoothly follow the movement of the object of interest and the display will be holding it in a fixed position for the whole frame. The result will inevitably be a blurred image of the moving object.

Quote:
"an image held on the screen for the duration of a frame-time [i.e. sample and hold] blurs on the retina as the eye tracks the (average) motion from one frame to the next. By comparison, as the [CRT] electron beam sweeps the surface of a cathode ray tube, it lights any given part of the screen only for a miniscule fraction of the frame time."

The degree to which all displays approximate a sample-and-hold effect is shown below: (thx to Xrox)


OLED (active matrix) - 100%
OLED (passive matrix) - 0.06%
CRT - 10%
Plasma - 25-40%
120Hz LCD - 50%
60Hz LCD - 100%





Another simulation below (trying to show differences accurately): blur is proportional to panning speed.
(Note: The second car picture above and the one below are the only simulations in this thread)



In the end, there is some good news for LCD when it comes to movies. Cinematographers follow strict guidelines that limit the amount of movement in a scene. Since LCD blur is proportional to movement it's usually kept at bay, but with games it's all to easy to overcome this with a flick of the wrist.

Also, blur can come from other sources beside the display itself. The blur found in most viewing content can almost level the playing field when comparing displays. To see what the display itself is capable of, PC/console games do a good job of eliminating extraneous blur.
post #2 of 196
Thread Starter 
On to "input lag".



Digital displays can suffer from image delay or "input lag" which can be measured with a Millisecond Stopwatch and a camera.
The average delay was 32 ms or 1-3 frames behind the CRT (PC signals only).
The average delay was 64 ms or 3-5 frames behind the CRT (Consoles and other ATSC/NTSC signals).
See this thread for input lag on plasma.



Download Adobe Flash Player

32 ms lag video: not bad at all





64 ms lag video: pretty bad




The average lag difference showed in real tests.
"Sheep dash" reaction test (below).




These settings made no significant difference on the average lag:

TV Game Mode
TV scaling
Running games
AMP on/off
V-sync on/off

TV input (HDMI/VGA)
Primary display choice
DVI output port choice
Green/Red clock colors



The average image delay can be directly added to ping time but unlike "ping lag", can't be compensated for by anti-lag game software. Off-line (single player mode) is just as much affected. Image delay has has been blamed on LCD Overdrive which needs to buffer incomming frames, causing a delay in output ("input lag" is actually "output lag").

In general frame buffers may be needed for:

Motion Compensation (AMP)
Overdrive
Scaling
De-interlacing
Reverse-telecine
Noise reduction
Color management
Image enhancements (DNIe ect)


CRT monitors are basically streaming devices with minimal/no buffering afaik.
They have the least lag - but some newer LCD monitors have caught up.
If it's possible with monitors, why not with TVs too?

A short list of lag-less LCD monitors from Digitalversus.com

Iiyama ProLite E2201W - 0 ms
Acer P223W - 0 ms
Iiyama ProLite E2403WS -1ms
Viewsonic VG2230wm - 1ms
Samsung 226BW - 1ms
The Viewsonic vx922 (discontinued) - 2ms




Besides increasing a player's reaction time, image delay makes the controls feel sloppy. Also, targets may not appear where they are supposed to be.
Below pics shows the differences in crosshair position during an average mouse sweep (the difference is proportional to speed)



Sweeping from left to right - each crosshair on a different lamp post.



Sweeping from right to left: generous hit-boxes are needed with the LCD
(the camera shows a double image on the LCD (frame transition).
post #3 of 196
Thread Starter 
120hz with AMP (much thanks to Spectra18, who works with standards converters, OreoJoe and Clau)

Note: This is about AMP (auto motion plus) artifacts on the LN-T4669/71. AMP can be turned off.
The AMP processor creates "motion compensated" frames which are inserted between each original frame.
"Motion compensation" means that for each inserted frame, moving objects in the scene are identified and shifted to the position they would be at the time of frame insertion.
The effect of all this is to reduce sample-and-hold blur & judder by at least half,
Turning it off will eliminate the artifacts below at the expense of more blur & judder.
AMP can also visually double the framerate of PCs/consoles.

AMP, otherwise known as MCFI (motion compensated frame interpolation) is complex and not without problems.
Besides the aforermentioned lag, there is "TBE" (the triple-ball-effect, so named here and best seen with sports content).
"TBE" comes from 120hz interpolation artifacts. It's hard to capture on camera.

TBE (triple-Bruce Willis-effect) - interpolation artifacts.



"TCE" (triple-crosshair-effect) below: "Resistance" on the PS3



"TTE" (triple-truck-effect) on a PC game below. Notice the funky crosshair.


Why "TBE"? The TV normally calculates new object positions for each new frame. When a scene is too complex to do that, the TV will simply combine the existing "before" & "after" frames to produce the middle one. Called "linear interpolation", it results in triple images (see the BeHardware article)
Quote:
Originally Posted by Spectra18 View Post

When the frame rate converter can't accuratley predict the in between frame or field it will exhibit a interpolated or blended image of the two.



Quote:
If an object is moving, it will be in a different place on each successive field.
As shown above, Interpolating [blending] between 3 fields gives 3 images of the object on the output field.
The position of the dominant image will not move smoothly; it will be seen as judder.



Sometimes the TV may decide to create new frames (instead of combining existing ones) but still guess wrong about an object's directon and placement. This is probably the original "TBE" and the result is again multiple images (thx to OreoJoe). Interlacing, compression and up-conversion artifacts can all help confuse the motion compensation process.







Quote:
If the motion vectors are incorrect, for example part of the figure is given the static motion belong to the background, then undesirable artefacts can occur which can sometimes look even worse than the results of linear interpolation.





Besides "TBE" there are sometimes "auras" around moving objects.






Above are three frame progressions. For the motion compensated frame, moving objects in the scene must be identified and shifted to their correct position in time by the TV (like a cut & paste).
If the TV registers motion but can't identify the object's outline (if obscured behind something or blurry as above) it may take part of the surrounding background with it while shifting positions.
The grating mis-match in the motion compensated frame above shows a sloppy cut-&-paste.


Movie frames purposely have camera blur (to smooth out motion) which may confuse the TV when identifying objects to be moved. Video games without artificial blur and slower games are fine but the interpolation doesn't keep up well with fast paced games, which leads to artifacts above.








Looking for all the info I can get on this. Post your comments.
post #4 of 196
IMHO, the color looks much better on the Samsung than on the Dell. The Samsung seems to show a yellow sunrise/set, the sky on the dell looks green/blue.
post #5 of 196
Nice posts and great photos! Thanks.
post #6 of 196
this just proves what ive already witnessed with my own eyes..that my 120hz $3500 sony xbr lcd lags behind my 10 yr old sony crt in important areas: LIKE DISPLAYING MOVING OBJECTS.

oh well.
post #7 of 196
great comparison photos.
post #8 of 196
Borf, excellent thread. Maybe we should send this to Samsung, lol.
post #9 of 196
I remember my old Toshiba Cinema Series 36" CRT with my 8300HD playing HD content. Sports were amazing, even with 480 lines of resolution. It's one reason I won't get rid of our 32" CRT flat screen in the bedroom.
post #10 of 196
Seeing posts like these make me worry when looking at upgrading TVs. I game alot, so I might just have to stick with my CRT
post #11 of 196
This is super noob question, but is this blurring only apparent on LCD TVs? or can it be seen on LCD anything, such as the LCD laptop screen im using right now. I get a lot of screen tearing just moving windows thats for sure. Is it possible that I just don't notice the blurring?

Also, how does this blur compare to that of a Plasma?
post #12 of 196
Wow, where can I find more information on these CRT type display devices? With a superior image (as shown above) they must be very expensive.
post #13 of 196
Quote:
Originally Posted by rhfb View Post

Seeing posts like these make me worry when looking at upgrading TVs. I game alot, so I might just have to stick with my CRT

I hear ya...still this close to buyinga 4665 though
post #14 of 196
The input lag is rather disappointing. Is this typical of LCD TVs or is this one particularly bad?
post #15 of 196
Thread Starter 
Quote:
Originally Posted by Luke M View Post

The input lag is rather disappointing. Is this typical of LCD TVs or is this one particularly bad?

Yep typical except for the Iiyama ProLite E2201W

Keep in mind I'm not bashing LCD here. Personally, the Samsung is much preferable for movies and the CRT is much preferable for games - just the way it is.

More TBE pics and stuff so check back
post #16 of 196
Quote:
Originally Posted by DynamicM3 View Post

This is super noob question, but is this blurring only apparent on LCD TVs? or can it be seen on LCD anything, such as the LCD laptop screen im using right now. I get a lot of screen tearing just moving windows thats for sure. Is it possible that I just don't notice the blurring?

Also, how does this blur compare to that of a Plasma?

That's your refresh rate. When you drag your curser across the screen slowly, you'll see a shadow and some blurring. It's very minimal on a laptop because the pixels aer so small.

1080p is basically 2 megapixels. When you compare a small 15" laptop screen to a massive 46" flat screen LCD, the pixels are 3 to 4 times as large and amplify everything. Then when you sit too close to a large flat screen, you even notice those artifacts even more.
post #17 of 196
Thread Starter 
Quote:
Originally Posted by studdad View Post

we should send this to Samsung, lol.

They definitely know - It's still perhaps the best LCD out there IMO.
post #18 of 196
I am new poster, but I have been reading these forums for a couple of months, so that I can make a good purchase for upgrading to an HDTV.

I am mostly a gamer and I have a PS3. It seems the market is trending towards LCD. I have checked XBR4 and Sammy71. However, the motion blur and input lag is unacceptable for me, especially towards fighting games where I need to be perfect on an 8-frame jab after blocking a 10-frame disadvantage attack.

I figured that perfect HDTV for me would be the SONY KDL-34XBR960. Two problems though: the TV is no longer produced and it's only 1080i (some PS3 games are in 720P and won't upscale to 1080i but downgrade to 480p instead).

As a result, I will still wait for an LCD that would be almost CRT-like in performance in motion blur and input lag. No HDTV upgrade yet. Maybe in CES, there will be a solution.

Oh... How about plasmas, RPs, and FPs? Are any of them better in handling motion blur and input lag?
post #19 of 196
Are we blind here - that puny CRT certainly demo's NO DETAILS - NO IMMERSION - and = NO HT WOW! Blahsville!!! BOring!!!

Is this a JOKE? CRT's is a dinosaur deserving of it's death!

BTW - My Sharp 57" has no Damn Stutter or Motion Issues and I owned the best CRT on the market 3 yrs ago and have zero regrets - 57" 16:9 vs. 36" 4:3 reflective CRT is crapola and no HT impact whatsoever! My Sharp blows away that CRT in every important area for HT viewing though it's blacks cannot match it - it simply is a NO CONTEST in every other respect for HT experience - the CRT had NO HT factor or Wow!
post #20 of 196
Input lag is so overrated.

I've had 4 LCD's in the past 2 years. AN Insignia, and 3 Samsungs of different models and specs. Only similarities are that they all have 8ms refresh and 60hz (aside from my 4071's 120hz).

Even playing online, I still rock the house in multiplayer. Input lag was never an issue.

Has for camera pannings, it's true. LCD's don't do those too well, unless you go with the 120hz, which help out a lot.

Even considering all the downfalls of the LCD, I would NEVER trade in my 4071 Samsung for ANY other TV (unless it was for a 52", lol). The 120hz and AMP makes games amazing, because of the simulated higher framerate. CRT's nor Plasmas can do that.

I rather play my games at 60fps with TBE issues, than play them at 30fps with no issues.
post #21 of 196
Ok quick question, so this TBE thing... .How long does it last?

Say Bruce willis is fighting crime, as he does, and all of a sudden he has a triple fore head...

Now does the tbe last for an hour? Minutes? Seconeds?

The way everyone talks about it as once it starts it doesnt stop until you have to forcefully stop the tv turning off the feature...

Can someone clarify?
post #22 of 196
Quote:


All of the newer display technologies such as LCD, plasma, DLP, and so on, have essentially a sample-and-hold characteristic. When a pixel is addressed, it is loaded with a value and stays at that light output value until it is next addressed. From an image portrayal point of view, this is the wrong thing to do. The sample of the original scene is only valid for an instant in time. After that instant, the objects in the scene will have moved to different places. It is not valid to try to hold the images of the objects at a fixed position until the next sample comes along that portrays the object as having instantly jumped to a completely different place. Your eye tracking will be trying to smoothly follow the movement of the object of interest and the display will be holding it in a fixed position for the whole frame. The result will inevitably be a blurred image of the moving object.

Quote:


"an image held on the screen for the duration of a frame-time [i.e. sample and hold] blurs on the retina as the eye tracks the (average) motion from one frame to the next. By comparison, as the [CRT] electron beam sweeps the surface of a cathode ray tube, it lights any given part of the screen only for a miniscule fraction of the frame time."

I've read these explanations several times, but I still don't understand them. Doesn't motion picture projection display a complete frame until the next one comes along...just like an LCD? And this is somehow "wrong"? The pictures illustrating sample & hold blur are somewhat disingenuous because they are simulations.
post #23 of 196
Thread Starter 
If there is one picture that should be paid attention to its the Pixperan "streaky picture test" as it shows exactly what I saw. Now that's me - supposedly people have different degrees of sensitivity to motion blur but I doubt it varies by much.

How much? I urge anyone to take this test - Let people see what YOU see.
When done, click "save streaky picture" and post it here (pic will be in the Pixperan folder)

Pixperan
post #24 of 196
Clue to stuttering?

The excellent BeHardware article linked to in post 1 may offer a clue to why there is stuttering. As explained in the article (based on measurement and Samsung info perhaps), if the processor fails to calculate the intermediate image because such calculation is too difficult, it may simply display the original frame. The measured lag then changes from long (calculation used, up to three frame periods, or 60 ms) to short (no calculation, only 10 ms lag at 50Hz frame rate). As a result, there could be a stuttering effect similar to what people observed, which is equivalent to input lag not being constant and jumping around (from 10 ms to 60 ms) as a function of the complexity of the images.

This stuff is very interesting.
post #25 of 196
Thread Starter 
I would bet that's right especially when you put it in numbers like that. "TBE" and "stutter" are definitely related. Well if Samsung couldn't find an answer that's the way it is for now.
post #26 of 196
Quote:
Originally Posted by jksgvb View Post

I've read these explanations several times, but I still don't understand them. Doesn't motion picture projection display a complete frame until the next one comes along...just like an LCD?

No, the projector light actually flashes (is blocked) at some multiple of the frame rate. LCDs with LED backlight can do this too.
post #27 of 196
Great post borf! You spent a lot of time on this and I'm sure everyone here really appreciates it. I agree with your analysis on how/why the TBE occurs. Hopefully Samsung can squeeze out a few more clock cycles on the processor to fix this. Either way I'm keeping my 5271 when it arrives.

-S
post #28 of 196
Quote:
Originally Posted by phanfave View Post

Great post borf! You spent a lot of time on this and I'm sure everyone here really appreciates it. I agree with your analysis on how/why the TBE occurs. Hopefully Samsung can squeeze out a few more clock cycles on the processor to fix this. Either way I'm keeping my 5271 when it arrives.

-S

Having a "few more" processing cycles WILL NOT fix it.
post #29 of 196
borf,

can you please run this test on every single HDTV ever made as well as each new HDTV as they are released?

you have quantified what I have been experiencing in my comparisons of CRT vs new HDTVs as far as gaming is concerned

it will be nice to know when HDTV finally catches up to the old CRTs (for gaming, westa settle down man)
post #30 of 196
Quote:
Originally Posted by isucamper View Post

borf,

can you please run this test on every single HDTV ever made as well as each new HDTV as they are released?

you have quantified what I have been experiencing in my comparisons of CRT vs new HDTVs as far as gaming is concerned

it will be nice to know when HDTV finally catches up to the old CRTs (for gaming, westa settle down man)

You don't ask for much, do you?
New Posts  All Forums:Forum Nav:
  Return Home
  Back to Forum: LCD Flat Panel Displays
AVS › AVS Forum › Display Devices › LCD Flat Panel Displays › 120hz LCD vs CRT - pics