Can more subpixels and clever video processing make a 1080p HDTV perform like an even higher-resolution set? To anyone who knows how a TV display works, that seems like an impossible proposition, but it's pretty much what Sharp is proposing with its new Quattron Plus series of televisions. But does it work?
That's what we've been wondering since January, when Sharp announced its new Aquos TVs with Quattron Plus technology at CES. At its press conference, Sharp pitched these sets as a more affordable bridge between standard 1080p models and pricier true Ultra HD TVs.
But these sets are expensive, especially compared with other major-brand 1080p sets—and even a few Ultra HD TVs—the same size. Since Sharp is clearly aiming its Quattron Plus (Q+) models squarely at consumers looking for step-up picture performance but who aren’t willing to shell out even more money for a true Ultra HD TV, we decided to see if they were a worthwhile investment.
For several reasons, we think the answer is no, though we do applaud Sharp's innovative processing technology that tries to improve on 1080p resolution.
We bought three of Sharp's Aquos Quattron Plus TVs—the 60-inch LC-60TQ15U ($2,000), the 60-inch LC-60UQ17U ($2,200), and 70-inch LC-70SQ15U ($2,700)—and brought them into our labs to answer two questions: First, does the Q+ picture enhancement technology really provide near-Ultra HD performance? And second, do these sets represent a bridge to a 4K future, since Sharp claims they can handle native 4K signals? We put all three TVs through our usual battery of lab tests to see their capabilities. What we found was pretty surprising.
Better than 1080p resolution?
With its Q+ technology, Sharp claims 10M more subpixels (not pixels, mind you) than a regular HD set. But do more subpixels mean more detail? To really get an idea of what Sharp is attempting to do, you have to understand some basics about display TV technology. 1080p TVs have about 2 million pixels, or individual picture elements, with each pixel made up of three subpixels—one red, one green and one blue, or RGB—for a total of 6 million subpixels. A video input signal then drives each pixel to a specific brightness and color to create the image you see on your TV.
In its regular Quattron TVs, Sharp adds a yellow subpixel creating an RGBY structure, which brings the total number of subpixels to 8 million. Sharp then addresses these subpixels in a novel way to generate a higher pixel count. But in this approach, the subpixels are being shared among pixels, which means that in theory a given pixel can’t be driven independently to full color, full brightness, or full detail without affecting an adjacent pixel.
But with special processing, Quattron Plus manipulates and scales image content in a clever way to take advantage of this new configuration to extend horizontal resolution while maintaining accurate color. Finally, these 8 million subpixels are split in half, effectively doubling vertical resolution and increasing the total number of subpixels to 16 million. More pixels generally translate into greater picture detail, but the question for us was whether more subpixels would result in more detail.
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Before we jump to our test results, let’s take a moment to highlight a display attribute that's not often mentioned when talking about picture quality: pixel structure. We don’t usually discuss pixel structure because you can’t really see it when viewing a TV from a normal seating distance. But if you were to look at any display from up close, you’d be able to see the individual pixels that make up the image. Using a magnifying loupe—as we did—you can actually see the repeating sequence of red, green, and blue subpixels mentioned earlier. The way these subpixels are addressed, their shape and arrangement, and even the gaps between them, can vary among different displays, reflecting the different technologies used. We’ve found that these variations can affect the way the finest image details are rendered on screen. With new Ultra HD sets, inviting viewers to sit closer, this level of scrutiny becomes increasingly relevant, particularly with regard to Quattron Plus processing.
When you look very closely at Sharp's Q+ TVs—as well as most Sharp TVs we’ve tested over the years—picky viewers may notice that the edges of objects aren't as smooth as we typically see on most LCDs, revealing a fine “honeycomblike” pixel pattern along the edges of image content, and even along edges of the TV’s screen graphics. A freeze frame from the "The Dark Knight" Blu-ray disc (Photo 1, above) illustrates this point.
In the zoom-in image of the highlighted red box (photo 2, above) for example, you can see the busy pixel pattern around the edges of the bat wing. Although this doesn’t affect the TV’s resolution or our assessment of the TV's overall performance, we’ve never regarded it as a plus, especially for those who connect a computer to their TV and sit up close expecting see crisp edges around fine text. The reason we bring up this point is because the first thing we noticed as we turned on Sharp’s “Resolution Enhance” feature is that the busy edges just described suddenly snapped into smooth clean lines, showing a clear improvement (see photo 3, below), more consistent with what we normally see on other LCDs. There was certainly something interesting going on with the Quattron.
For our official evalutaion of Sharp’s claims of enhanced performance, we tested each of the Q+ TVs with Ultra HD content from the following sources.
- Ultra HD (4K) content recorded on a Sony FDR-AX100 4K camcorder
- 4K patterns and videos played via a Redray 4K cinema player
- High-resolution 4K test images via the TV's USB port
- 1080p movies upconverted to the Ultra HD format via an Oppo 4K upscaling Blu-ray player
To get the Quattron Plus’ detail boost, you have to enable the “Resolution Enhance” feature; otherwise the TV performs like a regular HDTV. In the advanced menu, under picture settings, the Resolution Enhance feature can be set to “Mode 1” or “Mode 2,” optimized for videos or photos, respectively. Frankly, we didn’t see any performance differences between the two, though we noted that Mode 2 made the image dimmer. So we used Mode 1 for all our tests.
Using our Redray 4K cinema player, which outputs 4K signals via its HDMI 1.4 connection, we played native Ultra HD content on the Sharps and checked their picture performance with the Resolution Enhance feature on and off. (The Sharp TVs also have HDMI 1.4 inputs, which can handle 4K signals up to 30 frames per second, more on that later.) For comparison purposes, we also had a Sony Ultra HD TV (the 65-inch Bravia XBR-65X900A) and a 1080p LCD TV from LG (the 55-inch 55LA7400) in the room to see which of these produced picture quality closer to the Sharp.
The Redray 4K player comes with an interesting test pattern that provided an instantly clear demonstration of the Quattron Plus’ resolution capability. The test pattern—a crop of the center section of the pattern is shown below—is a series of concentric black-white circles (sine waves, actually) getting ever higher in frequency as they approach the center (much like a zone plate pattern but with frequencies in the reverse direction). The concentric circle pattern has detail going beyond the capabilities of 1080p, which was reproduced flawlessly on the Sony UHD TV (see the screen shot, photo 4, below). We were curious to see how the Sharp TVs would handle it.
With the Resolution Enhance feature turned off, the Sharp Q+ sets perform like a regular 1080p HDTV. This was confirmed by the visible V-shaped aliasing (interference) patterns present in the vertical (top and bottom), and horizontal (left and right) portions of the image (see photo 5, below). No surprises here. These moirélike patterns appear when UHD’s super-fine image detail runs up against the lower pixel density of the 1080p display, which was too coarse to reproduce the pattern’s extended detail.
But when we turned the Resolution Enhance feature on, something definitely changed. Horizontal resolution now extended to the limits of the pattern, with aliasing notably absent—much like what we saw on the Sony Ultra HD display. This was very impressive indeed—Sharp’s processing was clearly having an effect. But while horizontal resolution appeared very Ultra HDlike, vertical resolution was a different story. In the upper and lower parts of the image, resolution showed no improvement and aliasing was still present (see photo 6), which was disappointing.
Next we switched to the Sony FDR-AX100 4K camcorder to look at some live studio shots, which were sent to the TV via the camcorder’s HDMI 1.4 output. The Sony camcorder is capable of very high-quality 4K images, which we were able to confirm on the Sony UHD. On the Sharp, these images had a generally excellent, but inconsistent, level of detail, just like we saw with the test pattern. On various scenes, the detail along the vertically oriented edges of objects had better definition than we saw with the same content downconverted for display on a 1080p TV, or even on the Sharp sets when the Resolution Enhance feature was turned off. But other edges in the image that lay closer to a horizontal position were coarser and more jagged, lacking the smoothness we we saw when played back on the Sony UHD TV. Still, the overall impression was that the image was slightly sharper than we saw with the Resolution Enhance feature turned off, along with a sense that the pixel density of the TV was a touch finer than on the 1080p display.
4K test patterns and photos via USB
We loaded a number of our 4K patterns and still images onto a flash drive and plugged it into the TV’s USB port. In photo mode, the Sharp disables the picture controls so you can’t do any image tweaking except for a picture mode selection. Fortunately, the movie mode was very accurate so this wasn’t a concern.
With the Resolution Enhance mode active, 4K resolution photos did reveal some added texture when compared to the same image on a regular HD. The weave of the fabric in one photo was slightly better defined on the Sharp than on the 1080p TV in the room, and better than on the Sharp with its Resolution Enhance feature disabled. When we switched to a high-resolution graphic image, we could see that fine details, such as the whiskers of a cat, looked smooth and well defined when they were in a more upright position (thanks to the enhanced horizontal resolution), but these same whiskers became jaggy and choppy as they approached a horizontal position (due to the limited vertical resolution), consistent with what we saw in the earlier test pattern. As a result, the overall image detail was arguably a touch better than the HD image's, but no match for the smooth, seamless detail provided by the Sony UHD TV.
1080p on the Quattron Plus
We connected our 1080p test pattern generator to the TV to check regular HD performance. First up was our resolution test. With the Resolution Enhance feature off, the TV did an excellent job reproducing our resolution pattern with detail out to the limits of HD, as we expect from better-performing HDTVs. But when we turned the Resolution Enhance feature on, Quattron Plus offered a mixed bag, performancewise. Horizontal resolution was fine, but we were quite surprised to see some loss—as in less than 1080p—of vertical resolution. The concentric circles within our 1080p pattern (a different pattern than the one mentioned above) showed aliasing on the upper and lower edges, consistent with the loss of some vertical resolution. We also noticed that Resolution Enhance added moderate edge enhancement to the image that couldn’t be minimized, so there was slight haloing around objects that pickier videophiles may notice and find objectionable.
As we stepped through our test patterns, we noticed something very curious when we got to our “black levels” pattern. We normally use this pattern to optimize the brightness control (black level), and it includes a number of boxes with incrementally increasing brightness values emerging from black (see photo 7).
With the Resolution Enhance feature off, the pattern looked fine, and all boxes were clear and distinct (see photo 8, immediately below). But with the Resolution Enhance feature on, we noticed that the left and right edges of lower near black boxes were blurred (see photo 9, the lower image below). As the brightness control was incrementally lowered or raised, the blurring noise incrementally moved to the next box, up or down accordingly. We’d never seen this before and wondered if this issue would reveal itself on real world movie content.
We then connected our reference Oppo BDP-103 4K upconverting Blu-ray player to the TV with its video output set to output 1080p. With the Resolution Enhance feature on, we cued up a number of our reference-quality Blu-ray discs to see if they’d benefit from the Q+ treatment. In general, images on the Sharp were bright and richly detailed, and colors looked natural. Though we had witnessed some unusual red fringing on edges of the horizontal thin white lines of our overscan test pattern (an effect of the Resolution Enhance process), any concerns about the affect of subpixel sharing on real-world video were allayed. We paused on several highly detailed scenes, including a detailed cityscape, and here we did see some slight effects of the loss of vertical resolution, with a touch more jaggies along the diagonals of the building lines than we saw on the 1080p TV in the room. But we’re being super picky here, as this issue wasn’t distracting to any meaningful degree. The edge enhancement noted earlier was also present, and did give the image extra “pop,” which some viewers may prefer.
But perhaps the more significant detriment of the Quattron Plus processing showed up as we were playing the "Dark Knight" disc, and also with "Gravity." Both movies are filled with many dark, night time/space scenes, so the TV’s ability to reproduce shadow detail is really put to the test. And given what we saw with our black levels pattern, we paid close attention. We paused on several dark scenes in "The Dark Knight" (such as the screen shot in photo 10, below) and toggled the Resolution Enhance feature on and off to what effect the processing would have on real-world video content.
There was no mistaking it— the problem was there, and visible. With the Resolution Enhance feature off, as we see in the highlighted area shown in photo 11, an image with dark shadow detail —along with distinctive film grain overlaid on it—looks normal.
When we turn the Resolution Enhance on (photo 12, below), you can see how shadow detail is now visibly smeared horizontally. When we unfroze the frame and played the movie, the fixed smear became random “streaky” noise, which reminded me somewhat of the analog noise you used to see on VHS tapes. This problem was not present on brighter scenes, and on a variety of darker scenes it was sometimes difficult to detect, but when present it was apparent, and increasingly so when viewing from the sides due to the display’s increase in black level brightness at off angles.
We next decided to see what happens when we set the Oppo player to upscale the movie to the 3840x2160 format. While the upconverted Blu-ray image can’t produce the extra detail you’d see from a true Ultra HD image, we were interested in seeing how the TV’s processing would handle Ultra HD-format content. Unfortunately, the smearing of shadow detail we saw with the 1080p sourced content was also present here. On a positive note, Sharp applies less edge enhancement to 4K content than it does when upconverting 1080p. And speaking of upconversion quality, we found we preferred the Oppo's slightly crisper upconverted image to Sharp’s internal video processing, but they were close.
Last year when Ultra HD made its debut, we tested quite a few models, from several manufacturers. While we were impressed to varying degrees with their image quality, our biggest complaint was that almost all lacked the two key features that are now standard in 2014 Ultra HD sets: built-in HEVC decoding, and HDMI 2.0 inputs. HEVC decoding—also known as H.265—is a new, more efficient video compression technology that allows 4K content to be delivered to TVs over existing wires. Netflix is already offering some streaming content in 4K (including the second season of "House of Cards"), and other services are expected to follow. If your TV doesn’t include an HEVC decoder—and these Sharp Q+ models do not—you won’t be able to watch these 4K programs any time soon.
Also, unlike all the 2014 UHD TVs we've seen, the Q+ sets lack HDMI 2.0 inputs; instead, they come with HDMI 1.4 connections. HDMI 2.0 is important because it supports Ultra HD signals at 60 frames per second, which will be needed to view such programs via 2.0 compatible 4K players when they become available in the future. HDMI 1.4 is limited to 30 frames per second with 4K content, which is fine for most movies but not live sports.
As far as the Quattron Plus models, we were impressed by the innovative processing that does extend horizontal resolution, but we were disappointed the enhancement did not extend to vertical detail. Playback of 1080p HD content not only revealed a slight loss of vertical resolution, but it also introduced an unusual shadow smearing artifact that degraded the image on darker scenes.
To be sure, none of these issues were egregious enough to the point of distraction, especially if you’re viewing from eight or more feet away from the 60-inch screen, where they become undetectable. But at those distances, one could argue that the picture enhancements of Q+, or even the extended detail of Ultra HD, become less relevant. In the lab, we ultimately ran all tests on the Quattron Plus series with the Resolution Enhance feature turned off, as this provided the most neutral, artifact-free image. This is not to say that many won’t prefer the TV with the feature turned on, and we believe many will.
In our opinion, these Quattron Plus models, while interesting, are not really an answer for those looking for a significant performance boost over 1080p, or for those hoping to future-proof their TV purchase for 4K, especially given their price. Though the Sharps deliver a solid HD picture, the Q+ side of things (the part you’re paying extra for) falls short in performance and features when compared to the latest UHD TVs from other major brands—including those from Sharp. Value-wise, we think it makes more sense to buy a less-expensive, top-performing 1080p TV. But if you’re looking for a meaningful step up in image quality, and the latest features necessary to enjoy future Ultra HD programs, then we suggest you consider one of the late model, better performing true Ultra HD TVs, especially since prices for these sets will continue to fall.
For a full, detailed review of the Sharp Quattron Plus TVs, and to see how they stack up against the competition, visit our TV Ratings (available to subscribers), which currently have more than 120 rated models.
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