A curved screen has a major stylistic impact when furnishing an office or home. At the Consumer Electronics Show in January 2014, curved screens were among the top-rated attractions. Currently, all of them belong to the very high-end segment and are made with OLED technology. If we also consider the need to apply complex image processing circuits to compensate for distortions, we can conclude that they will remain an elite product for quite some time in the near future.

Of course! A 3D TV can also display 2D programs, i.e., SD and DVD (which in Europe are in 576p format) as well as HD and BluRay (which are in 1080i25 or 1080p50 mode). For this very reason, a 3D TV generally has a button to switch between 3D and 2D modes. Of course, an HD-only TV is not capable of displaying 3D programs. Depending on the technological choices regarding the representation of a 3D signal, an HD-only TV receiving a 3D signal may display images related to the left eye and the right eye side-by-side (side-by-side) or one below the other (top-bottom) or fragmented and arranged in an appropriate tiled pattern (tiled) or display nothing at all. The same would happen with a 3D TV set incorrectly in 2D mode.

Let us clarify the obvious case of three screens with the same diagonal, placed next to each other: there is a certain distance at which we can tell whether they have images of different resolutions. Let’s focus on the case of a single TV set. To distinguish between HD and Ultra HD, but also between SD and HD, one objective criterion is the minimum distance at which a viewer with normal visual acuity perceives the image on the TV without grain. This distance depends, of course, not only on the resolution but also on the diagonal of the TV set. There are some specific tables in this regard. Without having to resort to tables at this time, we can make a practical case that clarifies the idea. Let us imagine that we have a 42-inch television displaying a certain image and let us stand at a distance such that we can see the image without grain. Let’s gradually get closer: if at a distance of about 150 cm the image starts to “grainy,” we are looking at a standard definition image, otherwise, it is high definition. If I get about 75 cm closer and the image is still grain-free, we are looking at a 4K image.

The bandwidth resources needed to transmit 4K or 8K channels are not yet available. However, the problem is not only related to the lack of bandwidth availability but is also mainly related to the investment and time needed to upgrade the entire production, post-production, and distribution chain. For 4K there is currently at least one experimental “flagship” channel broadcast by each major satellite operator. However, there is also a problem with content availability, i.e., TV movies produced in 4K. Some 4K broadcasts are expected to be on the air by 2018. It would be a mere futuristic exercise to predict the timeframe for the availability of 8K broadcasts.

Since 2013, 4K resolution has been made available in high-end TVs but for the moment it is accessible only through satellite channels or through special media players, with a built-in hard disk or solid-state-disk, where 4K content may be preloaded at the factory time and more content can be downloaded from suitable network or cloud servers before watching. It is worth mentioning that 4K is the resolution of digital cinema (though, this comes at a 24Hz frame rate) which is gradually spreading in theaters equipped with facilities for secure and DRM-protected downloading of movies, normally via satellite. The 8K resolution is currently available in prototype displays and can be enjoyed only with content from shooting experiments. At the moment it is visible only on the occasion of demos, trade shows, and events. The UltraHD is not only a matter of spatial resolution (number of pixels) of displays, it is also about greater color depth, and higher temporal resolution (number of frames per second, not more than 25 or 50Hz of the HD, but also 100Hz and over). Audio experience comes with a very high degree of viewer involvement, being supplied by a system of 11 or 22 channels. The audio also becomes highly engaging, being provided in 11 or 22-channel versions.

Of course, these are programs and movies in digital format, otherwise they could not even get through the Internet. They can be standard definition (SD), but often also in lower definitions (especially when the terminal is a smartphone), or high-definition. Of the two main formats consolidated for high definition, normally format 720p is chosen (whereas for television broadcast, the preferred format is 1080i). It must be said, however, that for some time now programs and movies via the Internet are distributed in adaptive streaming mode: the actual definition is decided by the server, both depending on the type of user terminal and on the bandwidth actually available – and measured at subsequent time intervals – over the Internet client-server connection.

First of all, it should be mentioned that the satellite platform is capable of carrying far more channels than the terrestrial platform. The reason is purely technical, due to the inherently greater bandwidth of the satellite platform. For example, in a typical Italian region between 200 and 300 programs are available on digital terrestrial, while by pointing the dish to a specific satellite more than 1,000 become available. Adding to this technological reason is a market consideration: the spectrum allocated to digital terrestrial television services is very crowded, so it is expensive to allocate the available bandwidth to transmit high-definition. Satellite bandwidth, on the other hand, is available in larger quantities and therefore cheaper than the spectrum allocated to terrestrial television. However, high-definition can be expected to gradually supplant standard definition on all platforms, with the adoption of more bandwidth-efficient digital signal compression and modulation techniques.

Certainly, the improvement in image quality is not just a matter of subjective perception but is the effect of a greater amount of information actually available. The level of detail becomes five times higher than in the standard definition: it goes from a frame of 576 x 768 = 442k pixels to one of 1080 x 1920 = 2.1M pixels. The aspect ratio changes from 4/3 to 16/9, which is more natural for the visual angle of the human eye. The scene is wider horizontally (landscape format) and contains much more detail, giving more depth to the image. Also not to be underestimated is the presence of multichannel audio, which greatly increases the viewer’s sense of immersion in the scene. High definition is not only a visual experience but also an auditory one. HD resolution also lends itself to multimedia screens, which simultaneously present images, video, and text, as we are used to seeing on a PC browser or tablet.

Digital television is a technique of representing the video and audio signal in digital form, that is, as a sequence of binary digits. The digital video signal is unavoidable for computer storage and servers, but also extremely effective for a true broadcast-quality signal. In broadcasting, whether terrestrial or satellite, digital technology has been gradually adopted since the late 1990s, and today, in many countries including Italy, has completely supplanted analog technology, with which television had been going on for more than fifty years. Numerous experiments until the early 1990s had shown that a high-definition signal in analog format was impractical, although very attractive. Because of the efficiency of storage and transmission, high-definition television services are much better suited to digital technology. In this sense, high-definition is only one of the possible formats offered by digital television, which supports a whole family of formats: SD, HD, 3D, and UHD1 UHD2, as well as numerous other video formats available on the Internet.

HDTV (High Definition TV), is an umbrella term associated with a large family of systems for capturing and displaying television images of better quality than was traditionally possible on the home television set, called SDTV (Standard Definition TV). Although commonly image definition is linked to image quality, technically it is not: definition is an objective property by which television sets have been built and television programs broadcast for decades. Technically, the definition is determined by the number of elementary points into which the image is broken down, so it is a characteristic of the filming process. Definition referring to the quality of an image is also measurable as the number of pixels relative to size. Rather, the resolution is the degree of detail with which the image is rendered on the screen, that is, the number of lines and the number of points that can be placed on each line, so it is a characteristic of the display process.

To begin with, you need to make sure that high-definition broadcasting is available in your area, either through digital terrestrial, satellite, or broadband. The TV must have a display with high-definition resolution. You must also make sure that it has a built-in decoder capable of receiving HD signals, otherwise, you will have to connect the TV to an external decoder capable of receiving HD signals.