Since it’s an LCD display, the black level the Sony KDL-55HX823 is capable of depends on the intensity, and in this case, the scanning method of the light source.
For example, the user can raise or lower the [Backlight] setting to increase or decrease the intensity of the LED sidelights (the term “Backlight” is still used, although it’s technically a throwback to the days of LCDs which were actually back-lit). Additionally, the [Motionflow] system can be set to “Clear” or “Clear Plus”; these modes introduce side-light scanning in order to trick the viewer’s eye-brain into perceiving a clearer motion image.
We used the “Clear” [Motionflow] mode and a [Backlight] setting of 5, which resulted in the light output of a fully white screen measuring at 120 cd/m2. This is a good amount of brightness for a home environment, and under these circumstances, the KDL55HX823′s black level measured at a decent, but not exceptional 0.07 cd/m2. To demonstrate the flexibility of the controls, we could achieve a black level of 0.03 cd/m2 from the HDTV, but that would require more than halving the overall brightness (with the [Backlight] control), resulting in a very dim image. Still, the option is here to tailor the light output to your specific viewing environment.
To give some idea of how this fares against competing HDTVs from other brands, Samsung’s LED TVs are managing around 0.03 cd/m2 with a bright image, and the current kings in this area, the Panasonic Plasmas, reach down to 0.02 cd/m2 or even 0.01 cd/m2 – although their peak brightness is lower than the LCDs.
We investigated all of the [Motionflow] modes prior to calibration, and settled on “Clear”. “Clear Plus” almost halved brightness, for almost no perceptible increase in motion clarity. The other modes, “Smooth” and “Standard”, introduced obvious motion interpolation but without any side-light scanning, resulting in smoothed motion, but less clarity than the “Clear” mode. We used “Clear” for all video material. During the motion resolution test, it managed to render all 1080 lines on the scrolling chart distinctly, but with some small grey double images after the moving areas.
Despite this, with real-world testing of high motion video content, we felt that like other LCD-based TVs, the Sony KDL-55HX823, while producing good motion, didn’t match the clarity of any of the Plasma televisions we’ve tested. We understand that this is due to the fact that Plasmas actually emit no light from their screens for a fraction of a second during video frames, resulting in higher perceived motion clarity. With that said, neither technology handles fast motion perfectly, and some people complain of flicker on Plasmas, so LCD-based displays have their fans when it comes to motion rendering.
We had some trouble in assessing the extra-dimensional performance of the Sony KDL55HX823, since we couldn’t get the glasses to sync correctly with the 3D TV when we were playing back a 24fps 3D Blu-ray Disc. There was obvious crosstalk, coloured flickering, and little 3D effect to the picture when we attempted this test, and the only way we could resolve this and get some idea of the KDL-55HX823′s 3D capabilities was to enable [Motionflow], which, in 3D, seems to be a 60hz-based system. The “Clear” modes we used during 2D aren’t available in 3D, meaning that this introduced the so-called “soap opera effect” into films that previously had film-like motion. Sony wasn’t able to advise us as to what the problem was specifically, nor send us any new 3D eyewear in order to rule those out, so we had to continue the review using Motionflow to get a basic but incomplete idea of the 3-dimensional performance.
With this out the way, the 3D performance appeared passable, but not exceptional. As we often see with LCD-based 3D TV, one of the strongest attributes is the consistent Greyscale tracking, meaning that 3D images didn’t appear too obviously tinted, and had fairly natural colours. In fact, in the out-of-the-box state, the 3D mode shared the same blue tint that we saw in the uncalibrated 2D mode, which although not ideal, was reassuring (because we’ve seen some really wacky tinted images on past 3DTV displays). After calibration, the HX823 displayed the same natural grey shades, which acted as a canvas for fairly satisfying 3D video. Unfortunately, there is still a not unsubtle amount of crosstalk present, and although it’s not a deal-breaker, it’s noticeable.
Asides from the unfortunate problem we ran into with 24p content, the Sony KDL55HX823 did well on our 3D benchmark tests: it had no resolution problems in the horizontal or vertical direction, scaled Side-by-Side 3D TV broadcasts correctly, and didn’t have any problems with motion judder with European-style 50hz video (provided [Motionflow] was disabled).
SD processing left us without complaints – scaling was fairly crisp and clean, diagonal interpolation (jagginess concealment) was of a good standard, and the KDL-55HX823 successfully detected the most common Film-to-SDTV transfer cadences (for both PAL and NTSC) and rendered a jaggy-free image. A word on the [Film Mode] setting: with most TV manufacturers, this mode only pertains to film mode deinterlacing, but on Sony HDTVs, there’s a hidden second purpose. Selecting the “Auto1″ [Film Mode] will perform film mode deinterlacing on its own (this is the option we chose); “Auto2″ does this and also slips some motion smoothing into the bargain. We’re not a fan of this, so left it off.
The Sony KDL-55HX823′s performance with 2D HD material was good, and largely what we expected from an LED-sidelit LCD TV. Let’s start with the positives: Greyscale tracking (after calibration) was great, with the only uncorrectable problem being the common LED LCD problem of visibly blue (or purple, depending on where you’re sitting) tinted shadows. Measured Gamma (the distribution of light output from dark to white) was absolutely excellent, resulting in a picture that had a decent amount of “richness”. There were also no huge colour gamut inaccuracies, although the KDL55HX823 couldn’t fully saturate the blue colour, producing a slightly purple hue instead (again, something we often see with LED LCDs). All of these attributes afford the Sony HX823′s images a good amount of realism and depth.
There was also no unwanted video tinkering: any of the KDL-55HX823′s image-altering processes come with an “Off” switch, resulting in unadulterated video. The only thing of note is that the “Clear” [Motionflow] mode we selected does actually partake in some slight motion interpolation, which can very occasionally make itself visible with hand-drawn 2D animation. Again, though, it has an “Off” switch.
Panel uniformity has never been the strong-point of super-slim edge LED LCD televisions, and sure enough, the Sony KDL55HX823 revealed some uneven light distribution during dark scenes. In our review sample, the bottom right of the screen had some light spill visible, and the rest of the panel had some patchiness, with the top of the screen appearing slightly darker than the bottom. Viewers with large rooms should also keep in mind that, as an LCD-based TV, the KDL-55HX823 doesn’t excel at off-axis viewing. Users need to sit face-on to get the best picture quality, since blacks become slightly milkier, and colours become desaturated, if the TV is viewed from the sides.
In the “Game” [Scene] mode, we measured the Sony KDL-55HX823 as lagging by 31ms when we fed it 1080p/60 video. This is a fairly small amount of delay. Many users won’t notice any lag at all, but after reviewing HDTVs with only 16ms or around 22ms of processing latency, we can state that we do feel the difference. Games weren’t difficult to play on the HX823 at all, but the immersion was very slightly lessened compared to the faster displays on the market. Still, this is a good result and shouldn’t pose any problem for most users.
If we had to sum up Sony’s LCD (and LED LCD) output for the last few years in one word, we’d probably choose “decent”. And so it goes with the KDL-55HX823… other than the unusually slow menu interface, there’s nothing really wrong with it in terms of performance when compared to other LED TVs, but also nothing hugely exceptional about it, either.
Like many HDTV displays based on this technology, it produces decent black levels and an accurate picture, and suffers from the usual positives and negatives of LED LCD: in exchange for low power consumption and the ultra-slim profile, users will have to accept uneven brightness distribution across the screen, and some viewing angle limitations. The going rate for the Sony KDL-55HX823 online appears to be around £1300, which places it in a similar price bracket to the Samsung UE55D7000, an edge LED TV which shares very similar strengths and weaknesses. Users who are concerned primarily with picture quality, and who want a large-screen display, are still better served by Plasma televisions from both Panasonic and Samsung, in our opinion. LED LCDs have their benefits, most notably their very low power consumption and ability to produce very bright images, but picture quality appears to be lower down the list of priorities with this display type. If LED LCD is your thing, then the Sony KDL-55HX823 is one of many good choices in this category.
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