televisions

Sharp Aquos LC60SQ15U Q+ LED TV Review

60 in.

Solid core performance mired in eccentric engineering

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Behind The Screens

The Sharp LC60SQ15U is an odd TV. Not only can it display 4K content despite not actually being a 4K TV (3,840 x 2,160 pixels), its backlight is engineered specifically to exhibit a blue quality. For this reason, our hardware and software reported severe deviations in terms of white balance (black, gray, and white) and RGB (sub-pixel) balance.

In terms of dynamic performance, however, the SQ15U stands up to scrutiny: It produces solid black levels and is bright enough to combat even very high amounts of ambient lighting. Additionally, its gamma curve—which dictates how much luminance is added at each signal level—can be calibrated for optimal performance in either dark or bright environments.

Calibration

Calibrating the SQ15U was no easy feat, primarily due to eccentricities within its backlight control. In order to adhere to the proper white balance for HDTVs, tons of blue had to be removed from the sub-pixel balance. There are various "white points" that digital displays can adhere to, but the standard is called D65, and it's what TV content around the world is mastered to. The exact coordinates for D65 on the 1931 color space (x=0.313, y=0.329) adhere to a correlated "color temperature" of 6500K, hence the name.

To correct a TV's white point, I would normally begin by using a 2-step white balance control to correct the RGB balance. A display's 2-step control is what manages the dark and bright halves of the grayscale. After that, I would fine-tune my work using a 10-step white balance control, which would get into more detail and really iron out all the remaining kinks.

With the SQ15U, this process wasn't possible. Once I had tinkered with the 2-step controls, I entered the 10-step white balance controls to finish the job—only to find that the previous corrections I made with the 2-step controls were discarded. The SQ15U makes you choose one or the other, it won't let you use both sets of controls. Since I couldn't reduce the blue as much using the 10-step controls as with the 2-step, I wound up not using the 10-step controls at all.

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As one might expect, calibrating the SQ15U to HDTV standards required removing massive amounts of blue from its sub-pixel balance. View Larger

During the calibration process, we use CalMan 5 in combination with color and light meters to set a TV's luminance as close as possible to "black room" ideals: 40 fL (or 120 cd/m2) and a gamma sum of 2.4. I had no trouble honing down the TV's gamma sum, but completely correcting the exact gamma points along the grayscale was impossible due to the disconnect between the white balance controls. The TV's CMS (Color Management System) allowed for great flexibility in adjusting the hue and saturation of the primary and secondary color points, but the Value control (for color luminance) had no affect on the relative luminance of the points within the gamut as a whole.

How Q+ Works

The LC60SQ15U's unique ability to display a native 4K signal without actually being a 4K panel is made possible by Sharp's Quattron technology, which adds a fourth sub-pixel to the usual three sub-pixel setup. That probably doesn't make any sense—just bear with me for a moment.

Traditionally, digital displays have three sub-pixels, small rectangular transistors that make up each pixel, or picture element. Think of them like peas, and the pixel is the pod. Almost all digital displays use a red, green, and blue sub-pixel setup, but Sharp TVs add a fourth sub-pixel—yellow.

The Q+ TVs start with Sharp's four sub-pixel build and then split it in half, vertically. So while there are still 1,920 horizontal pixels and 1,080 vertical pixels, the actual sub-pixel count is drastically increased. Where "normal" 1080p TVs have 6 million sub-pixels, the Q+ TVs have 16 million sub-pixels.

A 4K TV has 24 million sub-pixels, so you can think of these Q+ TVs as "half 4K," at least in sub-pixel count. These extra sub-pixels allow the LC60SQ15U to play 4K content even though it isn't actually a 4K TV.

Contrast Ratio

A television's contrast ratio is determined by dividing its luminance at 100 IRE (peak white) by its luminance at 0 IRE (black). A higher number, preferably over 1000:1, complements numerous aspects of the display's picture quality, chiefly immersion.

I measured a solid black level of 0.065 cd/m2 within the SQ15U's Movie picture pre-set—this was with the Backlight at its default level. The corresponding brightness (using the ANSI checkerboard pattern) was a somewhat dim 94.72 cd/m2 –so if you're watching in a room with lots of ambient lighting, you'll want to turn up the Backlight to +16 or more.

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We measured solid black levels and a default brightness appropriate for a dim room.

Viewing Angle

Our viewing angle test measures a TV's contrast integrity at off-angles—when the contrast ratio falls below 50% of its head-on value at a particular angle, we consider this the limit of viewing flexibility.

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The SQ15U has a fairly standard viewing angle for an LCD television.

The SQ15U tested with a decent total viewing angle of 66°, or ±33° from the center to either side. You won't be able to watch from extreme off-angles like you would with a plasma or an OLED TV, but you can expect an average amount of flexibility nonetheless.

Color Gamut

A color gamut illustrates where a TV's colors fall (in hue and saturation) compared to Rec. 709 ideals. Errors in color production affect the balance and vivacity of whatever you're watching, and are often the difference between a good TV and a great TV.

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Prior to calibration, the SQ15U produces fairly accurate colors, though its green point is a little too saturated.

In Movie mode, the SQ15U exhibits accurate colors, though not without small discrepancies. You wouldn't notice oversaturated greens during most content, for example, but you might note clipping and blurring in a nature documentary with a lot of foliage—or worse, never know what you're missing. Using the TV's CMS (Color Management System), I was able to correct these small errors to ensure maximum detail retention and color purity.

What's more telling here is the TV's white point—it falls way outside of the ideal coordinates, skewing heavily into blue, which affects not only the purity/hue of whites, but of grays and blacks as well. Scenes with neutral tones, like a dark night sky, stormy clouds, or bright white snow end up tinted with a blue tinge.

Grayscale & RGB Balance

Our grayscale and RGB balance tests made the SQ15U's deviation from standard performance very obvious.

A television's grayscale refers to its range of black, gray, and white shades, and error within that grayscale is represented by a collective number called DeltaE. An ideal grayscale DeltaE is 3 or less—any more means visible deviation from standards. We measured a whopping DeltaE of 17.46—basically, every shade of the grayscale is tinged with blue. Using the TV's 2-point white balance controls, I was able to reduce this to 2.49, just below the acceptable ideal.

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With so much blue prevalent in its grayscale, the collective error prior to calibration was some of the highest we've ever seen.

Taking a closer look at that grayscale error, we can see where most of it comes from: an imbalance of emphasis within the red, green, and blue sub-pixel matrix. Blue is heavily emphasized throughout the entire grayscale, eventually growing so prevalent within the signal that the green sub-pixel is pushed almost completely out.

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Due to its slightly blue backlight LEDs, blue is severely over-emphasized within the RGB balance.

Gamma Sum

A gamma sum reveals how quickly (or slowly) a TV adds luminance along the grayscale as it travels from minimum luminance (black) to maximum luminance (white). Gamma sums range from 1.8 (where a display gets bright quickly) to 2.6 (where a display gets bright slowly), but most TVs adhere to 2.2, 2.3, or 2.4.

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The SQ15U is capable of adhering to both the 2.2 and 2.4 gamma standards—meaning it can be used in both dark and normally lit environments.

Prior to calibration, the SQ15U exhibited a gamma sum of 2.22—very close to the 2.2 standard, which is employed for environments with a medium amount of ambient lighting. During calibration, I used the display's 2-point white balance control to to edge it closer to a 2.4 ideal, which is better for a dim or dark room. Unfortunately, it was impossible to line up all of the points precisely because of the TV's 2-point/10-point control disconnect.

Our editors review and recommend products to help you buy the stuff you need. If you make a purchase by clicking one of our links, we may earn a small share of the revenue. Our picks and opinions are independent from any business incentives.
Our editors review and recommend products to help you buy the stuff you need. If you make a purchase by clicking one of our links, we may earn a small share of the revenue. Our picks and opinions are independent from any business incentives.
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Our editors review and recommend products to help you buy the stuff you need. If you make a purchase by clicking one of our links, we may earn a small share of the revenue. Our picks and opinions are independent from any business incentives.
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