Quantum dot LED is a new technology for producing displays. QD-LED or quantum dot displays - why they are the future

Nanotechnology in Sony's new generation TVs

In January, at CES 2013, Sony announced several new LCD TVs with Triluminos backlight technology. The new backlighting method should provide "rich, faithful colors, and excellent reproduction of the red and green parts of the color spectrum." If you dig deeper, it turns out that Triluminos includes “Color IQ” optical technology from the American company QD Vision using so-called quantum dots as backlight sources for the LCD panel.

What are quantum dots?

A quantum dot is a semiconductor whose electrical characteristics depend on its size and shape. How smaller size crystal, so longer distance between energy levels. When an electron moves to a lower energy level, a photon is emitted. By adjusting the size of the quantum dot, we can change the energy of the emitted photon, which means we can change the color of the light emitted by the quantum dot. The main advantage of a quantum dot is the ability to precisely tune the wavelength of emitted light by changing its size.

If you don't want to go into too much detail, you can think of quantum dots as miniature elements with unique properties, including the ability to emit light only in a specific, narrow wavelength range. Sort of like microscopic emitters that glow green, red or blue, depending on the size of the elements.

Red, green and blue spectrum of quantum dots

All TVs create images by mixing three primary colors: red, green and blue (RGB). True, Sharp also adds yellow, an additional color. But this in no way changes the essence of the system for creating a color image on a TV. Illumination sources with a strictly specified wavelength are more optimal in a lighting system than white light. The more accurate they are RGB colors backlight, the more natural the color shades on the screen will be. And mixing RGB sources in different proportions gives all possible color shades for the current television system.

Conventional LCD displays create these colors using color filters. Plasma displays create RGB colors using a phosphor that glows in one of three primary colors (they worked in a similar way CRT TVs). OLED TVs from LG and Samsung today use different methods. LG's technology uses white OLED sources covered with color filters. Samsung uses self-illuminating red, green and blue OLED subpixels.

So how is Sony using quantum dots?

Sony X9005 and W905 TVs

From models Sony TVs 2013, using quantum dots, backlighting is made in TVs of the X9005 and W905 Series. Traditional LCD LED models use blue LEDs coated with a special yellow phosphor to create luminous flux in a relatively wide band, with a spectral maximum in the yellow region. Which is quite efficient compared to other technologies (eg CCFL LCD and plasma), but still wastes a lot of energy.

Triluminos uses blue LEDs, but they are not covered by a yellow phosphor; the blue light from the LED passes through an IQ optical element containing red and green quantum dots. Thus, blue LEDs perform two functions: creating a primary light source and exciting red and green quantum dot sources. About two-thirds of the light energy from blue LEDs is used to excite quantum dots.

The figure schematically shows the principles of operation of traditional lateral LED backlight LCD panels (above) and backlights on Sony Triluminos TVs. In a traditional system, light from a white LED source propagates along a light guide along the panel (behind it) and, reflected from the reflector, illuminates the pixel cells of the panel. In the lower figure, the principle of light propagation is the same. But in Triluminos, blue LED light passes through red and green quantum dots.

Some may remember the "Triluminos" branded TVs that Sony previously produced using color LEDs. But the 2013 version of "Triluminos" is not only distinguished by the use of quantum dots. Today at Sony models Triluminos uses an edge-lit LCD panel design, whereas 2008 featured a full array of RGB sources behind the panel.

What do quantum dots do on TV?

Sony claims that compared to LCD TVs using white LEDs, its new technology illumination expands the color gamut towards potentially achievable shades, i.e., in the presence of appropriate video sources. But since all modern TVs are capable of fully reproducing all the color shades found in standard video sources, this statement is in some sense a marketing hyperbole.

However, the new technology has advantages, even if we ignore the annoying marketing and the benefits expected in the future with the advent of video sources with advanced color scheme. When we evaluated the color rendering of REC calibrated. 709 projectors with LED sources noted that the color RGB LEDs looks more natural than a similar one created using color filters ( DLP projectors), two-color mirrors (LCD/LCOS projectors) or mercury projection lamps. One of the TV technology specialists noted that the light from LED sources is like a painting painted with purer colors.

And some cnet.com reviewers, when testing conventional LCDs LED TVs note in their reviews a bluish tint on the screens, compared to, say, plasma displays. This effect tends to be most noticeable in dark areas, but I have noticed a slight bluish "coolness" in both brighter materials and flesh tones. In some cases, this is noticeable even despite the seemingly excellent color according to the measurement results.

So, it is likely that with the same measured color accuracy results, the picture on displays with quantum dots will be more realistic. But how much is unknown? But won't mixing oversaturated colors lead to other problems? How will the color filters that are still used on the LCD perform when the backlight is “pure” color? Answers to these assumptions and questions should be sought in reviews of the new X9005 series TVs and any other backlit TVs. quantum dots.

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The current generation of quantum dot technology in TVs uses a primary light source, like the blue LEDs in Sony Triluminos. But this is not necessary and will not always be so. Quantum dots can also be excited directly. Thus, it is possible to create an LCD panel backlight system entirely based on quantum dots. But quantum dots can be used for more than just illumination. It is also possible to make a directly self-luminous display, similar to OLED displays. But instead of organic LEDs, self-emitting quantum dots of three primary colors will be used. QD Vision calls these displays “QLED,” and they can have features similar to what OLED displays exhibit today (such as infinite contrast). Will they be able to provide more better color rendition and less power consumption? On this moment, It's not clear yet. Given the technological challenges in mastering the mass production of OLED TVs, it is very encouraging that there is another technology on the horizon that could have similar potentially exciting capabilities.

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Conclusion

Unlike many new technologies demonstrated at trade shows today, quantum dot technology is already in real use and has good potential for further improvement. Currently, quantum dots are only used in the backlight systems of some of Sony's top LCD TVs. But, like displays based on OLED sources, they can become a promising basis for future displays. As much as possible? Wait and see.

Many new display technologies are being demonstrated at international exhibitions, but not all of them are viable or have the appropriate capabilities for successful commercial implementation. One of the pleasant exceptions is quantum dot technology, which is already used in the backlight of LCD displays. It is worth talking about this technical innovation in more detail.

Quantum dots

Quantum dots are nanoparticles of semiconductor materials. Their parameters are determined by their size: as the size of the crystal decreases, the distance between the energy levels increases. When an electron moves to more low level, a photon is emitted. By changing the size of the dot, you can adjust the photon energy and, as a result, the color of the light.

This is not a new discovery; in fact, quantum dots were created more than thirty years ago. But until recently they were used only in special scientific instruments in laboratories. Strictly speaking, quantum dots are microscopic elements capable of emitting light in a narrow wavelength range. Moreover, depending on their size, the light can be green, red or blue.

By changing their size, you can finely control the wavelength of the emitted light. This technology, used in modern models televisions, dates back to 2004, when the QD Vision company was organized. Initially, the staff of this research laboratory tried to use quantum dots to replace organic dyes when marking various biological systems, but then they decided to try the technology on televisions.

This idea was soon joined well-known companies. In particular, in 2010, researchers worked together with LG on the QLED project. However, the very concept of technology in relation to LCD TVs was constantly subject to changes, its working name also changed several times. A year later, in collaboration with Samsung, a prototype of a color screen based on quantum dots was created. However, he did not go into series. The latest implementation of this concept is part of Sony's Color IQ technology, which introduced the Triluminos backlit screen.

As you know, all LCD TVs create a picture by mixing basic colors - red, green and blue (RGB model). Sometimes yellow is added, which, however, does not significantly affect the system of creating pictures on the LCD screen. Mixing RGB colors in LCD TVs is carried out using color filters, and in plasma panels- thanks to the phosphor.

In classic LCD models, “white” LEDs are used as backlight. The color in the white spectrum, passing through color filters, gives a certain shade. More advanced models use phosphor LEDs that emit light in the blue region. This light then mixes with yellow to become visually white. To create the same on the screen from a similar white, respectively, red, blue and green filters are used. This is quite effective, but still wastes a lot of energy. In addition, here engineers have to look for a certain balance between color rendering quality and backlight brightness.

Advantages of quantum dot TVs

Two years ago Sony company for the first time presented mass-produced models of television devices with Triluminos backlight, in which quantum dots are implemented. This is, in particular, the KD-65X9000A. The backlight uses blue diodes, but there is no yellow phosphor. As a result, blue light, without mixing, directly passes through a special IQ element that contains red and green quantum dots. The manufacturer calls the main advantages of the technology deeper color rendition and minimization of losses in brightness.

It is expected that, compared to LED backlighting, quantum dots will provide an increase in color gamut by almost 50 percent. The color gamut in the new Sony TVs with Triluminos backlighting is close to 100% NTSC, while models with regular backlighting have about 70% NTSC. Thus, it can be stated that quantum dot backlit TVs can indeed improve image quality, making color reproduction more realistic.

But how much more realistic? After all, it is known that in the same Sony TVs the picture is created using the usual filters that mix colors? It is quite difficult to answer this question; a lot depends on the subjective perception of image quality. In any case, the happy owners of the first Sony TVs with the new backlight note that the image on the screen looks like a painting painted with purer color paints.

The fact that other leading companies immediately joined in the implementation of this technological innovation confirms the fact that quantum dots are not solely a marketing ploy. At CES 2015 Samsung company introduced SUHD TVs, which also implemented similar technology. It is noted that the new TVs provide higher image quality at a lower price than OLED models. LG also presented TVs with quantum dot technology (Quantum Dot) at the ULTRA HD exhibition.

The comparison with OLED is not accidental. After all, many companies first turned to OLED technology as a way to improve the image quality of modern TVs, but encountered problems with their production when launching them into series. This is especially true for OLED TVs with large screen diagonals and ultra-high resolution.

In the form of quantum dots, a kind of backup option was found - the color gamut on such TVs is almost as good as on OLED displays, and there are practically no problems with the industrial development of the technology. This allows companies to produce TVs that will rival OLED technology in picture quality, while remaining affordable to a wide range of consumers.

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3. Samsung SUHD TVs 2016: Quantum Dot technology
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Quantum dots are semiconductor crystals ranging in size from 5 to 10 nanometers (slightly larger than the size of a DNA molecule). Depending on the size and material from which the nanocrystals are made, under the influence electric current or light they emit different colors. A 10-bit matrix of new Samsung TVs allows you to display up to 1 billion color shades, which makes color reproduction incredibly accurate and rich.

How is Quantum Dot technology different from others?

What benefits does Quantum Dot technology provide? The first LCD TVs were inferior to modern ones in both brightness and color reproduction. LCD TVs with LED backlight last generations made a significant step forward in terms of increasing brightness, but did not provide ideal color reproduction.

OLED technology is a compromise solution that provides high-quality color reproduction, but at low brightness. The use of quantum dots allows you to achieve maximum results both in terms of color rendering and brightness, without any compromises. Quantum dot displays reproduce the brightest and most realistic images.

Samsung SUHD TVs use quantum dots as their light source. They emit light that produces natural colors and creates a realistic image.

Quantum dot technology was developed to overcome the shortcomings of OLED. Thus, Quantum Dot screens use materials of inorganic origin, which have a significantly longer service life. And for TVs that have been in use for 7-10 years, this is important. In addition, TVs based on Quantum Dot technology completely avoid the burn-in problem that occurs when using OLED.

Quantum dot technology has been implemented in the following lines of Samsung SUHD TVs, available on Russian market: top-end KS9000 (curved) and KS8000 (flat) with diagonals from 49 to 78 inches, as well as the KS7500 (curved) series with diagonals from 49 to 65 inches and KS7000 (flat) with diagonals from 49 to 60 inches.

Nano coating technology Samsung screen Ultra Black allows you to absorb glare from the light reflected by the screen, even in a brightly lit room.

What else is used to improve the image?

In addition to quantum dots, Samsung SUHD TVs use several other important technologies to improve picture quality. For example, Ultra Black technology, which is implemented in new television panels, the structure of which is similar to that of a moth’s eye.

Such design feature allows you to minimize glare on the screen, reducing the reflection of external light by up to 99.7%, and increase contrast by 35%. As a result, the viewer can enjoy excellent black depth when watching TV during the daytime, even in a well-lit room.

HDR 1000 technology (right) provides exceptionally accurate color reproduction across a wide range of shades and high level detailing.

Another technology embodied in Samsung SUHD TVs in 2016 is HDR 1000. It allows you to recreate realistic dynamic range brightness, maintaining rich colors in both dark and light areas of the image. As a result, if a frame contains both very dark and very light areas, they will look much more natural than on a TV screen without HDR support. The peak brightness of new Samsung TVs is 1000 nits, which is reflected in the name of the technology. But to enjoy the HDR effect, you need appropriate content.

RGB vs RGBW panels: which one to choose?

TVs with 4K resolution have appeared relatively recently. At the same time, there are already devices on the market with different types matrices For example, there are models that contain only RGB pixels (used in Samsung TVs), and there are panels that have a white pixel added - RGBW. A user who does not understand technological intricacies is unlikely to sense a catch here.

And it exists and is as follows: if in a TV with an RGB matrix each pixel consists of three subpixels of red, blue or green, then in an RGBW matrix there are 75% fewer such pixels. In the rest, one of the primary colors used in displays to form a full palette of shades is replaced by white. As a result, in such TVs only a portion of the pixels are capable of displaying all shades.

Within the framework of the Display Quality Measurement Methodology (IDMS) developed by the ICDM organization, the Contrast Modulation (CM) or “Contrast Modulation” indicator is notable, which allows us to talk about how fully the display is able to display the picture.

This figure for RGBW TVs is one and a half times lower than for RGB: in the first case it is 60%, in the second - 95%. In some countries, contrast modulation information is already provided along with resolution information.

Without special measuring instruments, you can also notice differences in image quality: for example, when clear boundaries color transitions, on TVs with an RGB panel they are displayed correctly, but on RGBW the edges of the transitions present a slightly ladder-like structure.

In addition, when an RGB signal is displayed on an RGBW matrix, some color information is lost, as a result of which the film will appear in front of you in a slightly different form than what the director intended.

Photo: Manufacturing companies; PlasmaChem GmbH; Samsung Electronics

IN Lately Along with this, technology is gaining popularity, which we recently talked about on the pages of Mediasat. This time we want to introduce readers to quantum dot technology.

As journalists from The Conversation UK write, the Korean electronics manufacturer LG set the tone for everyone else by announcing at the January CES 2015 exhibition the upcoming release of ultra TVs to the market. high definition(Ultra HD) with displays that use quantum dot technology, an improved method for producing color displays.

What exactly is a “quantum dot”?

The technology, which has become a significant new step in the production of displays after , is to pass rays of blue light through nano-crystals ranging in size from two to ten nanometers (nm), which absorb light of one wavelength and emit light of another, specific wavelength . Each dot, depending on its size, emits light of a certain color. A film consisting of quantum dots having the dimensions necessary to emit red and green light is placed in front of the screen backlight unit. Achieving a glow effect using quantum dots narrows the wavelength of the resulting red and Green colour, which means reducing the amount of light blocked by the LCD filter. This means that we get clearer color reproduction and more vibrant colors.

Cadmium quantum dots produce a particularly pure green color. NASA

With its announcement, LG is ahead of other manufacturers who want to gain a leadership position by improving contrast, saturation and expanding the color gamut (the range of colors that a display can reproduce) - that is, everything that the use of quantum dots can provide. All this makes these displays ideal for viewing high-definition and ultra-high-definition content, as well as for all those who work in the field graphic design, photo and video production.

Transition to a new level of TV quality

The transition to Ultra HD television does not only mean increasing the number of pixels and producing higher resolution screens. Manufacturers and broadcasters want to provide an environment in which the video and photo images delivered to the viewer have the highest possible dynamic range while maintaining economic profitability for the producer.

And this is not something from the “distant future” series. In fact, the new standards - that is, what is needed to implement any new technology - have already been clearly defined. The ITU-rec 2020 standard for ultra-high-definition television provides for broadcasting TV programs at speeds of up to 120 frames per second, with a higher bit rate, as well as with an expanded color gamut and improved contrast.

Currently, content known as “high-definition programming” is streamed at a resolution of 1920 x 1080 pixels, with a specific frame rate, color range and contrast that allows it to be played back seamlessly on any compatible display. However, both the broadcast and film industries are already capable of producing material whose quality exceeds the approved standard. The problem now is that there are not enough devices on the market that could display video material in such high quality - and therefore, there is little point in producing a large amount of content that is not particularly worth watching.

Thus, the use of quantum dots expands the capabilities of ultra-high-definition displays, allowing high dynamic range content to be transmitted to viewers in the future. There are also additional benefit: Quantum dots are much cheaper than all other competing display technologies High Quality– such as OLED, organic light-emitting diodes. At past CES, the technology was loudly touted as the next great technology of the future, but it appears its star has begun to set before it has even fully risen into the sky.

Currently, quantum dots are only used in combination with other illumination technologies, but it is possible to develop methods that allow them to be used as a separate technology. In any case, since 2015 and in the near future, the world's best quality video and photo content playback in high resolutions will be associated using quantum dots.

With this material we are just opening a series of articles about the top line of Samsung TVs of 2016 - and in each of them we will reveal in a little more detail the essence of the key technologies and features inherent in them: quantum dots, HDR 1000, Smart TV, curved display along with the proprietary 360 design °. Today we're talking about about the current top model in the family - KS9000.

KS9000, however, incorporates the entire complex latest achievements Samsung in the field of creating LCD TVs is a kind of pinnacle, the standard of this technology. First of all, the effect is achieved through the latest LED backlight technology using quantum dots. Let's talk about it in more detail.

⇡ Video review of the 2016 Samsung SUHD line

⇡ Quantum dots

Semiconductor nanocrystal technology has long attracted imaging engineers. More precisely, it attracts the physical dependence of the emitted light wavelength (and, accordingly, color) on the size of the crystal. This is very convenient, you just need to grow the necessary crystals, and voila! - we have a source of pure color radiation without filters.

And we learned how to grow crystals just a few nanometers in size! In 2011, Samsung for the first time presented a prototype of a TV that displayed images solely due to self-luminescent quantum dots. True, it remained a concept, a hint of future great achievements. And for now we see a transitional stage.

The Samsung SUHD TV of the 2016 model year uses classic liquid crystal technology using VA-type matrices - and quantum dots are assigned only the role of a layer between liquid crystals and LED backlight. The latter makes crystals ranging in size from 3 to 7 nanometers luminesce - and yes, they do it in different colors.

Another effect of using Quantum Dot instead of light filters is the absence of loss of brightness on them. In addition to this, a special layer works between the diodes and the “quantum” diffuser, generating additional light. As a result, Samsung claims an honest 1000 nits for its KS-series TVs - and you can trust this number. TVs with quantum dots simultaneously show more shades, more accurately follow the author’s idea of ​​color rendering, and at the same time turn out to be brighter - and in the latter case, the separation from OLED models, which have inherent problems with brightness, is especially noticeable.

Let's move on to the story about the Samsung KS9000 itself.

⇡ Design and interfaces

Televisions are the same gadgets as, for example, smartphones. And the trends in their design are exactly the same: smaller frames, thinner edges, more metal in the design. The style of the 2016 line was named “360° Design” - not because the back of the TV has the same screen as the front (although there are such experiments), but because of the visual “flow” of surfaces one into another, as if without joints . We won’t describe the concept in detail, we’ll just admit that the Samsung KS9000 is beautiful: the front panel is entirely occupied by the screen, the back is elegantly polished, and the thickness is a few millimeters.

It has become significantly smaller than before, but includes a full set of necessary interfaces: 4 × HDMI, 2 × USB, optical audio jack, antenna connectors. On the TV itself, in addition to the One Connect port itself, we see another USB, Ethernet and a Common Interface expansion slot.

Another feature is the lack of visible buttons. They are hidden on the bottom edge, right under the luminous plaque with the name of the manufacturer.

Let us also note the elegant metal leg: if usually this detail does not evoke any emotions - anyway, flat-panel TVs are designed to be hung on the wall, then for a curved model, placement on a cabinet looks more relevant.

A special charm is how the engineers were able to place the speaker output in the gap between the leg/wall mount rod and the body. A very elegant solution.

There is no point in writing about the dimensions - they depend primarily on the diagonal. The KS9000 comes in four sizes: 49, 55, 65 and 78 inches.

⇡ SmartTV and remote control

TVs learned to connect to the Internet and provide direct access to various gaming and Video-On-Demand services more than seven years ago - all this time the system was only being honed, finally turning the device from simple way playback images to your home entertainment center.

For control, a remote control is used that is unusual in shape, but quite traditional in content - with a minimum of keys, but capable of controlling many devices at once.

The latter is achieved through the Smart Hub concept - the TV recognizes what exactly is connected to its ports and allows you to control the receiver, Blu-ray player, and so on, without changing the remote control. It is very comfortable.

We will tell you more about Smart TV from Samsung from 2016 in one of the following articles, but here we will focus on the key points.

At the heart of everything is a quad-core processor, which provides not only shell speed and multitasking, but also extremely high-quality processing of the signal coming from external sources. Taking into account the need to work with the most complex HDR signal and the ability for HDR upscaling (more on that later), there is more than enough work for it.

Among other things, the KS9000 has a built-in full-fledged media player that can play files in MKV containers, MP4 and M2TS, and with full support for HDR video - all that remains is to find this very video in some way. A huge reserve for the future.

When you turn it on for the first time, the Samsung KS9000 asks for permission to connect to any available Wi-Fi network - naturally, there is a wireless module. Next, we get access to a significant number of installed applications, the number of which will only increase with system updates. The branded Smart TV is based on its own operating system Tizen, which was previously planned to be actively implemented in Samsung smartphones- now it primarily services televisions. The already mentioned multitasking, speed and low risk of catching a virus while surfing the web (due to the low prevalence of the OS, they are practically not written for it) are its advantages. But just in case Samsung case also uses anti-virus software - problems with malware there should not be from the word “at all”.

The interface of both Smart TV and the settings menu is extremely concise and simple. Among the proprietary features, we highlight the ability to preview popular/recommended videos from other applications on any screen. The range of services is extensive: Netflix, ivi, OKKO, Megogo and many others.

It is also possible to play without a connection external device- and in two ways. Or in simple arcades in standard application“Games”, or games at the PS4 and Xbox levels through streaming content delivery on the GameFly service. To use it you need to have account Samsung.

⇡ Picture

Samsung has not disclosed the specifications of its TVs for quite some time, refusing to talk about contrast or minimum black field luminosity. This, however, does not mean that the terrible truth is being hidden from us - it’s just that at one time the endless race of numbers led to rather ridiculous results when companies were measured by contrast ratios measured in millions to one. It was impossible to confirm or refute these numbers regarding the so-called dynamic contrast, but the real, static contrast was several thousand to one. And this is a very good result.

With the advent of the HDR standard (we will talk about it in more detail in one of the following articles), increased resolution also made sense - when, in addition to a simple increase in the number of displayed pixels, a significant increase in detail in the shadows and highlights of the image was added (that is, extended dynamic range), the picture became look truly impressive.

The native resolution of the KS9000 panel is naturally 3840 × 2160. By using 1152 backlight units, we obtain a high level of dynamic contrast with minimal flare for an LCD. The contrast, depending on the user mode, is around 4000:1 - 5000:1. And not at the expense of brightness, which even in cinema and game mode, configured primarily to achieve maximum black depth, reaches 500 cd/m2. In addition to this, the panel is equipped with an Ultra Black anti-glare layer. According to the manufacturer, it absorbs 99.7% of external light. It’s not easy to believe, but the fact is that there is practically no glare, it’s comfortable to watch TV in daylight, even with the backlight not turned up to the limit.

Two more important advantages of the KS9000 are the highest smoothness of motion display and response time. These are only visual, subjective impressions, but no artifacts, blur or trails are noticeable. There will be no problems in gaming mode either - in fact, LCD panels have always had a decent response time, and this VA is no exception.

And of course, as befits a top-end TV of 2016, there is a curved panel, which some like, some don’t, but its implementation is very good. Thanks to Auto Depth Enhancer technology, the depth of each plan is worked out separately, optical distortions are reduced to a minimum.

⇡ Conclusion

Samsung KS 9000 is, if not the logical limit of LCD technology, then at least the obvious peak at the moment. Featuring a 10-bit panel, a unique quantum dot filter, and HDR 1000 technology that delivers previously unavailable extended dynamic range, the rest technological advantages, such as native 4K, high contrast levels, almost perfect motion processing and the beautifully implemented Smart TV of 2016, even fade into the background. An excellent TV in every way.

We express our gratitude to the Samsung brand store in GUM for the opportunity to shoot