Setup: We began as always by setting up the Samsung LN-T4681F for optimal image quality in our completely darkened theater. After setting maximum light output to a comfortable 40 FTL and adjusting black levels accordingly, we tweaked the set's white balance controls to closer approach the standard of 6500K--although the default Warm2 setting measured relatively close to begin with. After calibration the grayscale measured relatively linear, although it did dip a bit into red in very dark areas.
As we mentioned above, we also noticed one unusual issue with LED Motion Plus. Engaging the feature automatically pegs the backlight control at the maximum setting. In and of itself this isn't a big deal because on the LN-T4681F, as opposed to conventional LCDs, you can still achieve optimally dark black levels with a high backlight setting since the backlight actually turns off (and you can set maximum light output using the contrast control, so you don't lose any adjustability). The problem is that when we turned off the TV while LED Motion Plus was engaged, then turned it back on again, maximum light output jumped from our ideal 40 FTL to about double that, without us touching an adjustment. Weirdly, simply selecting LED Motion Plus in the menu, without even turning it on or off, was enough to re-attenuate the backlight back to 40. Because we didn't want to have to remember to do that every time we turned on the TV, we decided to leave LED Motion Plus turned off. We don't consider that a big loss anyway since we had a difficult time spotting image lag even with the feature turned off.
(Update 12/10/2007: Since this review first posted, Samsung sent us a firmware update that resulted in the TV maintaining its Motion Plus setting. Click here or scroll down to the tips section of this page for details, which also includes a tip detailing our full user menu settings.)
After getting every setting to our liking we sat down to compare the Samsung directly with a few other HDTVs we had on-hand, including Pioneer's PDP-5080HD and PRO-FHD1 as well as Samsung's own FP-T5084--all 50-inch plasmas--along with a pair of LCDs: Sony's KDL-46XBR4 and JVC's LT-47X898. We slipped Transformers into our Toshiba HD-XA2 HD DVD player and sat back to see how the LN-T4681F stacked up.
Black levels and color: Here's the pull-quote: The Samsung can produce the deepest shade of black of any flat-panel HDTV we've tested, regardless of technology. When the screen faded to black or showed a mostly-black background in our completely dark, black-walled test lab, the TV basically disappeared. That's because the LED backlight actually turns off when there's nothing on the screen, whereas the other plasmas and LCDs in the room still emitted light. Screens rarely stay black for long, however; what really matters is a TV's black-level performance with actual program material. To gauge that we compared the Samsung directly with our current reference for black level, the Pioneer PDP-5080HD.
Black areas in most scenes, such as the letterbox bars above and below the picture, the void of space around the spinning Cube during the Transformers intro, and the shadows under the wing of the troop transport plane and in the depths of the cabin, for example, appeared slightly darker on the Pioneer. Don't get us wrong; the difference wasn't night and day (or even 10 p.m. and midnight), but when we paid careful attention to both over the course of the movie, the Pioneer did win in most cases. We could coax a deeper black out of both sets by reducing their brightness controls, of course, but doing that obscured details in shadows. The Sony, for its part, still managed to display a respectable level of black, but it was slightly outpaced by the other two. Those three HDTVs, in turn, produced better black levels than the other sets in the room. To sum it up, while the Samsung definitely produces the deepest shade of black in isolated circumstances including mostly black scenes, the Pioneer still holds the crown for best overall black-level performance with the majority of mixed-brightness program material.
A quick aside for the geeks: The discrepancy between the Samsung's black levels showing a fully black screen vs. real program material was supported by further testing. For instance, the Samsung's black screen was immeasurable by our KM CS-200. However, when we looked at a standard checkerboard pattern--which includes both white and black, and so better represents actual program material--the Samsung's blacks were not only measurable, but lighter than the Sony's and the Pioneer's. We suspect the main culprit here is blooming (see below), where the bright white squares next to the darker ones spoiled that absolute black. Either way, these objective tests jibe with our subjective experience, which is that the Samsung gets extremely dark on full-black screens, but that performance doesn't translate to the very best black-level performance with most program material.
Back to Transformers: As the sun set on the tarmac after the mysterious chopper lands, we had a good opportunity to appreciate the Samsung's superb shadow detail. For example, we could make out the camo of the shadowed soldiers and details in the Decepticon's jet engine; it all looked quite natural yet packed with the punch only great contrast can deliver.
We did see one small fly in the black-level ointment, however. The LEDs produced what's known as "blooming," when a bright onscreen item exceeds its boundaries and brightens the dark areas immediately adjacent. When the Transformers title came up in a field of black, for example, or when Earth spun around to be cut off by the black letterbox bars, the black areas next to the lettering and the planet brightened in comparison to the other sets in the room, which exhibited no blooming. In most scenes, however, blooming was difficult to detect, especially outside the letterbox bars, and we never found it outright distracting except when we watched the set from off-angle. We also expected the Samsung, since its LEDs do vary in intensity, to fail our black-level retention test, but it passed with aplomb after calibration; the levels of black and near-black remained constant relative to one another regardless of the brightness of other areas of the screen (blooming notwithstanding).
The Samsung LN-T4681F evinced superb overall color accuracy, surpassing both the Pioneer PDP-5080HD and the Sony. Its solid grayscale and excellent primary colors combined to rival the color reproduction of the PRO-FHD1, our current color reference, and its black levels contributed greatly to perceived saturation and richness, easily outdoing the FHD1 in overall punch. The grass and trees around the Pentagon and the lake, the blue sky above the choppers in the desert, even Jon Voight's ruddy mug looked natural, realistic and rich, and the ubiquitous midriff of Mikaela Banes looked deeply tan without a hint of sunburn.
Video processing: As we expected, the film looked incredibly sharp and well-detailed, although, as usual, we did not distinguish any difference in detail between the Samsung and the other sets in the room, including the lower-resolution Pioneer, which looked every bit as sharp, from our seating distance of about 7 feet. According to test patterns, the LN-T4681F delivered every line of 1080i and 1080p sources when set to Just Scan mode. Like many sets we've tested, it did not deinterlace 1080i film-based sources properly, and in our one real-world deinterlacing test, the end of Chapter 6 of Ghost Rider, the grille of the RV showed more moirÃ© and artifacts than we saw on sets that passed, such as the JVC and the PRO-FHD1. As always, spotting other instances of the effect of improper 1080i deinterlacing was difficult, and we don't consider this failure a major issue.
(Update 12/10/2007: Since this review has first posted, Samsung sent us a firmware update that resulted in the TV properly deinterlacing 1080i film-based material. Click here or scroll down to the tips section of this page for details.)
We also didn't notice any serious instances of motion blur or image lag during the film, regardless of whether we engaged LED Motion Plus, which supposedly helps prevent such lag if it occurs. Looking at our favorite ESPNHD ticker, the edges of the letters looked a bit softer on the LN-T4681F than on the other TVs regardless of what setting we chose for LED Motion Plus. On other program material we watched, however, the Samsung maintained a sharp image, even during the quick action of a basketball game and the lightning activity of the big set-piece fights in Transformers.
Other performance considerations: All of our observations of LN-T4681F's picture quality were made, as usual, from the sweet spot directly in front of the TV with our eyes lined up with the middle of the screen. From off-angle, however, the LN-T4681F's black levels grew noticeably less black, which, of course, impeded saturation, too. We've seen the same effect on all LCDs we've reviewed, but on the LN-T4681F it was quite a bit more noticeable. When we moved just one seat over on the couch, for example, the letterbox bars and black of space in the opening "Cube" section appeared appreciably brighter than on the Sony seen from the same angle. From extreme angles, the Samsung's black areas looked brighter than any TVs' in the room; blacks on the Sony, again, stayed much truer from extreme angles. The Samsung's blooming effects also became more noticeable when seen from off-angle. Given its poor off-angle performance, videophiles who want to experience the LN-T4681F's best picture quality will have to really duke it out for the sweet spot (luckily that stand swivels!). As always, the plasmas in the room looked basically the same from any angle.
Compared with most other LCDs we've tested, the LN-T4681F exhibited very good uniformity across the screen, although not quite as good as the Sony. Looking at gray-field test patterns, the only issue we saw was a tendency in mid-dark fields (about 25-15 IRE) for the left and right sides of the image to appear brighter than the middle. This issue was difficult to spot in program material, so we don't consider it a big deal.
Like that of the LN-T4665F, the LN-T4681F's shiny screen proved a distraction. We could see ourselves reflected in the screen when the picture showed any moderately dark material while room lighting was moderate to bright. As we type this passage watching an NBA playoff game, for example, the silver strip lining the edge of our laptop, as well as our orange shirt and even the beige universal remote, are visible in any dark areas, including the circle of the Spurs' court and the Blazers' uniforms. None of the other sets in the room, including the plasmas, reflected as much ambient light. We asked Samsung whether the shiny screen had any impact on contrast ratio, and while the company's reps explained that some benefit to the CR spec is derived from the screen's supposed ability to limit interference from ambient light, they said the LED backlight's local dimming was a much larger factor affecting CR. We'd love to see a version of this set without the reflective screen, but we'll probably have to wait till next year for that.
As we've mentioned before, standard-def TV programs can often arrive via a high-definition resolution (depending on your cable or satellite box), which can make a high-def TV's standard-def processing a moot point. For people who do connect a true standard-def source, however, such as the 480i component-video input we used, the LN-T4681F will deliver a slightly below-average performance. It did poorly on the jaggies tests, doing little to smooth out the edges of diagonal lines or the stripes in the waving American flag. While it had no trouble resolving every line of DVD resolution, fine details like the stones in the bridge and the grass appeared a hair softer than on the Sony and the Pioneer, for example. When we looked at HQV's noisy shots of skies and sunsets, we saw that the Samsung's four levels of noise reduction had a very slight impact from one to the other, although in some areas we could discern the benefit of using High as opposed to Off. We still recommend leaving it in Off unless video noise becomes bothersome. Finally the set engaged 2:3 pull-down quickly and effectively, cleaning up the moirÃ© in the grandstand behind the racecar.
With PC sources originating on DVI and connected to the Samsung's HDMI port, the LN-T4681F performed extremely well, as we expect from 1080p flat-panel LCDs. In Just Scan mode the set resolved every detail of 1920x1080 sources according to DisplayMate, with no overscan and excellent sharpness in 10-point text and other fine details. PC performance dropped off a bit when we switched to the set's analog VGA input; while resolution was still full with no overscan, onscreen objects appeared a bit softer, and we detected some interference in the highest horizontal resolution patterns. We were frankly surprised by the dropoff in analog PC quality because Samsung's 1080p sets, both plasma and LCD, are usually superb in this regard, but at the end of the day it won't matter to most users. The analog VGA input is still perfectly serviceable for casual connections, and serious PC users will want to go in via HDMI anyway.
|Before color temp (20/80)||6812/6864||Good|
|After color temp||6598/6496||Good|
|Before grayscale variation||+/- 427K||Good|
|After grayscale variation||+/- 98K||Good|
|Color of red (x/y)||0.641/0.324||Good|
|Color of green||0.306/0.596||Good|
|Color of blue||0.151/0.064||Good|
|Black-level retention||All patterns stable||Good|
|Defeatable edge enhancement||Y||Good|
|480i 2:3 pull-down, 24 fps||Pass||Good|
|1080i video resolution||Pass||Good|
|1080i film resolution||Fail||Poor|
|Samsung LN-T4681F||Picture settings|
|Picture on (watts)||194.65||112.57||112.03|
|Picture on (watts/sq. inch)||0.22||0.12||0.13|
|Cost per year||$59.83||$34.90||$37.77|
|Score (considering size)||Good|
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