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
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
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):
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.
"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.