But, I’ve not read any explanation of WHY all the 60Hz LCDs HD GURU has tested, the following HD GURU finding is true: “Tests conducted by HD GURU demonstrated how, in the presence of motion, 1080-lines of resolution (per frame height) dropped to 320-lines or less on displays featuring 60Hz refresh rates, which was long the standard.”

1) Why do 60Hz LCD panels display half of what would be “expected.”

a) Expensive LCDs with, I assume, a good deinterlacer: 50% of 1080-lines measure about 660-lines.

b) Cheap LCDs with, I assume, a poor deinterlacer: 50% of 540-lines measure about 330-lines.

HD GURU has also reported a Samsung LED-based HDTV, when ME/MC (motion estimation/motion compensation) is turned-off — measured resolution drops back to about 660-lines.

AS SOMEONE POSTED: “turning on AMP things change, but for me, and for everyone who had see HD content in my set, everyone can tell that image detail had improved greatly, i cannot see any image degradation at all, only when I turn AMP off picture looks worse, and I´m only talking about detail.”

This would seem to indicate that there is “something” about LCD panels that allows only half of the lines sent from the deinterlacer to actually be displayed EACH time the panel is refreshed. I’ve studied LCD technology and I can’t find anything that would explain how each refresh (1/60th second) of an LCD panel would display half of what a plasma or DLP can display each refresh. (This would imply an inherent problem with LCD technology.)

HD GURU further states: “By speeding up the refresh rate from 60Hz to either 120Hz or 240Hz, set makers reduced or virtually eliminated motion blur.”

It seems everyone claim it’s the 2X/4X/8X rate that reduces motion blur — assuming motion blur from LCDs is “real,” if I believe it is the ability of LEDs to quickly turn-on and turn-off that really reduces motion blur. (This Dynamic LED mode is separate from ME/MC on/off in the Samsung.) The brief “on” time mimics the behavior of plasma displays.

In fact, a 120Hz refresh-rate is dependent on the panel having a fast 8ms update time which ITSELF minimizes motion blur. (Panels that run at 480Hz have a 2ms update time which is near plasma times.)

If I’m correct on both points, the real function of the interpolated frames is to increase average brightness since brief “on” times would cause these HDTVs to look too dim. In short, the marketing is backwards: high-refresh rates compensate for the actual motion blur reduction technologies.

2) Many folks are upset about how 120Hz “destroys” the look of film. First, as I understand it, there are several ways 24p is converted to 120Hz; some HDTVs keep 2-3 pulldown (60Hz with pulldown) is doubled to 120Hz — while other HDTVs repeat each film frame 5-times. (Only the latter eliminates the undesired look of pulldown. This distinction seems to be lost in most of these discussions!)

Unfortunately, in my opinion, the very high 120Hz refresh-rate — verses film’s 48Hz — does create a “video” look. (Which is why 100Hz PAL TVs make film look like a bit like video.)

The solution would seem to be to turn-off ME/MC when watching 24p film or video. (The video will, of course, still contain pull-down.) However, from reading the HD GURU tests, as soon as an HDTV is switched 60Hz — resolution under motion drops in half which is definitely not what is wanted. Which brings us back to the first question. What is it about LCD displays that prevents displaying 1080-lines when running at 60Hz?

There are two other questions:

The real solution to good looking film presentation is to operate an LCD at 72Hz because it would allow pulldown to be removed and yet have a refresh rate that mimics a three-bladed film projector shutter. This would NOT require an interpolator as each frame would simply be repeated twice — after the first presentation. Which in turn would eliminate ME/MC artifacts.

5) Are there any LCD HDTVs that offer 72Hz for 24p and 120Hz for 30p and 60i? (There is at least one plasma that does this.)

If, for some reason, 1080-line LCDs panels can only present half a 1080-line frame, then it would imply 96Hz might be needed so there would be three repeats — after the first presentation. Unfortunately, 96Hz is really too high — which means the best solution is to get LCD panels to display 1080-lines on EACH update.

The Samsung interpolator must be able to generate 1080-lines to match the real frame on either side. Yet HD GURU reports, “In addition, it appears that none of the ME/MC chips available to set makers are capable of processing all of the data within the original film frames needed to produce artifact-free synthesized ones. Therefore, to achieve image consistency, the LCD panel must degrade the actual frame’s image quality to match that of the synthesized frame, which is why the test pattern shows the degradation.” This would imply that at 120Hz HDTVs should show less resolution at 120Hz than at 60Hz.

6) Is HD GURU saying that the interpolator generates 1080-lines, but each frame is full of artifacts? Or, is HD GURU claiming the interpolated frame has lower resolution — which conflicts with the measurement of nearly 1080-lines from the Samsung.

PS1: Of course, for those who think 24p is “old-fashioned” ME/MC will be seen as an advantage. But as long as films are being made at 24fps I’m not interested in trying to “fix” an industry problem in my HDTV.

PS2: “If the source material was recorded on film, the frame rate is 24fps. If it’s from videotape or a video camera, the frame rate is 30fps.” Simply not true. HD VIDEO is often 24p and interlaced video has a FIELD rate of 50 or 60. This is why 50i and 60i are so smooth. Motion blur is a function of shutter-speed which can, and often is, set independently of frame-rate.

What good are the black levels on LCD/LED TVs when they *always* have screen uniformity issues? Plasma displays black, just black without any clouds or flashlights. Dark scenes on LCD/LED TVs are just distracting, period.

What good are the black levels on LCD/LED TVs when they *always* have screen uniformity issues? Plasma displays black, just black without any clouds or flashlights. Dark scenes on LCD/LED TVs are just distracting, period.

When I go through the shopping stores looking at LCD/Plasma TVs, I allways wander why is it that TV manufacturers insist in “motion estimation”, “motion compensation” and “image improvement filters”… and would like to sugest another path to get the best image in your TV products!

In my opinion, poor image quality (artifacts and bluring) only appears when viewing analog tv signals, compared to the same signal whatched on a CRT TV; or when viewing digital video that was improperly converted from its analog source.

I think that ME/MC (motion estimation/motion compensation) and other “image improvment filters” almost allways degrade the image instead of improving image, because ME/MC/”image
improvement” seems to take place on improperly deinterlaced video and/or improperly converted video/film to digital from its analoge video source, and therefore these methods
will add noise to the original image witch will result in image artifacts and/or bluring.

To get the best image, LCD/Plasma TV manufacturers should concentrate their effords on good analog to digital tv signal convertion and proper deinterlacing methods (see http://www.100fps.com/).

Things like 24p should be adressed only when converting film from tape to digital format, TVs shoudn’t do anything about 24p.
When converting TV video signal to digital, proper resolution should be adopted according to its analog source characteristics…

“All analogue sources output 576 active lines per frame (PAL) or 480 active lines per frame (NTSC). Capture devices process line by line into pixels, so one line becomes one row of pixels. Because of this, only two vertical sizes are suitable for capturing: full and half: 576 and 288 (PAL) or 480 and 240 (NTSC). Any other size will cause the device to cap all lines anyway and resize them afterwards. Since vertical resizing by capping devices in general gives very ugly results you should not do this. When you cap at half vertical size, capping devices just discard every second field. (Note: the official NTSC vertical resolution is 486, but all capture devices crop this to 480 lines.)”
-in guides from http://www.doom9.org (see http://www.doom9.org/capture/introduction.html)

So to convert analog TV signal to digital and mantain its original 4:3 aspect ratio, the folowing resolutions shoud be adopted:
PAL: 768×576
NTSC: 640×480
it should be properly deinterlaced (see http://www.100fps.com/) and only than should it be rescaled to the LCD/Plasma native resolution.

Hoping to see LCD/Plasma TVs with better image quality in the future,
Best Regards