If the transition from black and white to colour television was, all in all, quite painless, the shift towards high definition or high definition that you say you want, it promises to be rather problematic, at least in our country. Those who want to buy a new TV, LCD or plasma today, capable of viewing video in high definition are only spoiled for choice.

But if you look a little deeper into what the market offers and, above all, the availability of content, you realize that there is still very little to see. In Italy, only Sky regularly broadcasts five channels with HD programs and, although it started more than a year ago at the World Football Championships, managed to convince only a fairly small percentage of its subscribers to satellite service: 200 thousand in all. The other national broadcasters, starting with RAI and Mediaset, have been committed for years not to become too competitive and do not seem to be very interested in the subject.

An alternative source of content is the evolution of DVDs, but here the problem is the existence of two different standards, Blu-ray and HD DVD, strongly defended by their supporters, both electronic equipment manufacturers and content manufacturers, Some timid attempt to unify the two standards has not led to any outcome and the availability of content is one of the factors that will be able to decree the success of one standard compared to the other, just as happened in the past with the standards for videos

The uncertainty about which the winning standard will be slowing down the offer of high definition titles that is still quite limited, a few hundred for each of the two standards and only a fraction of these are now available also in Italian. The situation is complicated by a clear case of conflict of interest: one of the most important developers of the Blu-ray, and therefore holder of the relative rights of use, is Sony who controls a substantial slice of the A film company that publishes its titles in Blu-ray format is therefore indirectly paying for its direct competitor and that is the reason why it has pushed names like Paramount Pictures and Dreams to take sides in favour of HD D format The match also extended to the video game console market where Sony is present with the PlayStation 3, equipped as standard with a Blu-ray player, while Microsoft’s Xbox 360 can be equipped with an HD DVD player.

The latest sales data are a slight advantage for Blu-ray discs and to counter this trend Toshiba currently offers only in the United States an HD DVD player at less than $200, half the price of the cheapest Bluray players Microsoft, for its part, has launched a promotion on the Xbox 360 player for Christmas, which is provided with five high definition titles, a promotion also valid for Italy. The two standards therefore seem to coexist for a few years and, fortunately, players are already available capable of handling indifferently Blu-ray and HD DVD discs, such as the LG BH200 or the Samsung BD-UP5000, which

The lack of certainty seems to be the leit-motiv that is accompanying the introduction of high definition. At the root of all is the fact that, while for standard television signals (the ones received today with antennas on the roof or generated by a VHS VCR or a DVD player) each country has adopted a single well defined format. To begin with, HD signals differ in the number of horizontal lines that make up images, 720 or 1,080, and in the number of images contained in a second of videos, from a minimum of 24 to 60. In addition, each image can be made up of two so-called semi-squares or fields, one containing odd lines and the other equal ones, and in this case we speak of interlaced video signals to differentiate them from progressive ones, in which each image is treated as An acronym like 1080/50i therefore indicates a video signal with images composed of 1,080 horizontal lines, transmitted in interlaced mode with 50 semi-squares per second, that is 25 complete images, while the acronym 720/50p refers to signals of 720 lines in progressive mode containing The first is today the preferred standard for most television stations, while for recording fi lm on Blu-ray or HD DVD, progressive signals are used, generally identified with the 1080p.

A first attempt to make it a bit less difficult for consumers was made by the association EICTA, which collects the largest European manufacturers of electronic equipment, which proposed the use of the HD ready logo. In order to be able to use this logo, the television or the projector must have a 16:9 format panel composed of at least 720 lines vertically, but must accept in input also signals at 1080i and be equipped with an input in analog or HD component

HDMI (High Definition Multimedia Interface) identifies the standard for digital connection of equipment while HDCP (High-bandwidth Digital Content Protection) is the standard protocol of the copy protection system. An alternative to the HDMI interface is the DVI (Digital Visual Interface), which is widely used in computer applications: with special adapters, it is possible to connect DVI output equipment to devices with HDMI input or vice versa. In essence, the HD Ready brand simply certifies the ability to display the video in high definition when the device is connected to an external video source, but does not give any guarantee of the quality of the images. For example, when you display a signal at 1,080 lines on any device with a lower resolution, you need to resize it, which can be done in different ways and with results that can be significantly different in quality. When the HD Ready brand was proposed, about two years ago, the devices capable of displaying signals at 1,080 lines without any resize were very few. The situation has changed radically, however, so much that some manufacturers have started using brands like Full HD to distinguish televisions or video projectors with panels of 1,920 x 1,080 pixels, that is, capable of displaying HD signals to 1,080 lines without resizes The EICTA, perhaps a little late, is trying to put the HD Ready 1080p brand right in order to identify this type of equipment, with HDTV 1080p reserved for those equipped televisions.

This decoder should not be confused with the digital terrestrial television decoder, which is increasingly being supplied by the flat screens on the market today and is only suitable for standard video. If these screens are to be used in future for the reception of high definition broadcasts, an external decoder will be required. As mentioned in the opening, the offer of flat screens is very wide and there are two technologies.

The market is contended with: plasma and LCD (Liquid Crystal Display). Although the quality of the images produced can be comparable, at least if the best screens belonging to the two categories are compared, the physical principles on which they are based are different.

Plasma screens are composed of tiny cells, grouped three to three to form the single point that composes the image. Each cell contains a gas which, if electrically stimulated, causes the light to be emitted of one of the three basic colours (red, green and blue) by the substances covering the walls, which are completely similar to the phosphors used in the cathode ray tubes of traditional television sets.

In the LCD screens, the light is emitted by a series of worescent lamps behind the panel and the layer of liquid crystals behaves like a variable shutter. The light then passes through a matrix of coloured filters, also these grouped in groups of three to form the single point of the image. In some recent models, such as the Samsung LE 40M91B, the worescent lamps have been replaced by high brightness LED sets, which have the advantage of ensuring better panel uniformity and more faithful colour rendering.

The first generations of both technologies suffered from several limitations, either in whole or in part overcome in the most recent flat screens, so much so that it can be difficult to distinguish a plasma from an LCD at a glance. In particular, the phenomenon of burn-in that caused the appearance of ghost images in the first plasma screens is virtually absent in the most recent models, or at least in the most valuable ones, while the refinement of manufacturing techniques allows today to create cells of size For comparison, the first 42-inch plasma TVs had a resolution of 848 x 480 pixels, while some recent Panasonic and Philips models also reach 1,920 x 1,080 pixels. If resolution has never been a big problem for LCDs, there were other limitations of the first generations of these screens, in particular due to reduced contrast, limited viewing angle and high response time, all limitations that can be considered exceeded by the best LCD screens on the market today The colour rendering, which was much less than the plasma screen time, has also improved considerably. LCD screens are also available with smaller dimensions, up to 22 inches for a Full HD like the Sharp of the Aquos P series while for maximum dimensions, the limit is determined only by how much you are willing to spend: for both

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