How they work
Plasmas are usually heavier and in larger housings, and produce excellent picture quality which allows them to handle fast moving images very well. So for fast moving action, some sports, for example. Plasma can be a better choice. One negative point with Plasmas is they can suffer from “screen burn” where a single motionless image will be “burned” into the display if left for too long.
An LCD display is made up of an LCD panel containing millions of tiny pixels, behind this panel sits a fluorescent white backlight.
Each pixel consists of a shutter and a coloured filter, of which the shutter is used to control how much of the white backlight can pass through it and uses the coloured filter to determine what colour is displayed. The millions of pixels combined make up the image that you see. Due to the nature and response speed of LCD’s, the picture quality is not so good on video and fast motion images, although new technologies from the major manufacturers are aiming to remove any issues. Some succeed quite well.
The newly released LED screens are technically not made using LED for the image pixels, but the LED term refers to the replacement of the fluorescent white backlight with LED backlighting, of which there are two methods. Dynamic RGB LEDs, which are positioned directly behind the LCD panel (providing a better contrast ratio but slightly less definition), or white Edge-LEDs positioned around the rim of the screen, which uses a diffusion panel to spread the light evenly behind the screen.
Plasma screens range from the most common size of 42″ right up to an impressive 103″ with larger sizes constantly being developed. At the time of writing, Panasonic’s’ 152″ is the largest plasma in the World, although not yet commercially available.
Newer plasmas are lighter than their predecessors, however, they are usually around 10% heavier than LCDs due to the glass panels. The newer LED LCD Panels are usually lighter, and much thinner than the other types.
As plasma pixels can be controlled to emit no light at all they produce deeper black levels, which define contrast. Even when an LCD pixel is switched off, light emitted from the backlight escapes leaving blacks a dark shade of grey. Plasmas also produce better greyscale subtleties that reveal more detail in dark picture areas.
The bright nature of LCDs make primary colours appear instantly vibrant. Plasmas produce natural, more accurate colours with a wider range of subtleties across the spectrum.
Motion rendering was considered to be better in plasmas as faster pixel response times cope with fast-paced action better.
Older LCDs suffered from blurred edges and streaming trails, however most new LCDs feature anti-blur technology. LCDs with a 120Hz refresh rate are fairly common, with high-end LCDs offering a 240Hz refresh rate.
A faster refresh rate enables video to look smoother. Plasmas do not need to use this type of processing.
The two standard resolutions of high definition are 1280×720 and 1920×1080. They are often referred to as 720p, 1080i and 1080p. The number stands for the number of horizontal scan lines, while the letters refer to either i for interlaced or p for progressive, with progressive being the better of the two.
Today, Plasmas and LCDs are typically advertised as being either “HD Ready” or “Full HD”, and these terms reflect the native resolution of the plasma/LCDs panel.
“HD Ready” typically means the native resolution of the panel is 1366×768, meaning it is capable of showing full 720p but has to compress higher resolutions to fit.
“Full HD” refers to having a native panel resolution of 1920×1080 and is capable of showing full, uncompressed video at 1080p.
In the domestic market, high definition is transmitted using the HDMI interface. This type of connection supports any kind of video format and up to 8 channels of uncompressed audio. It has a maximum cable length of approximately 10 metres.
In the professional market, high definition is transmitted most commonly using HD-SDI, although HD-SDI only supports up to 1080i. When 1080p transmission is required, Dual-link HD-SDI can be used. HD-SDI is known to be reliable at lengths of up to 80 metres.
Most professional plasma/LCD displays have interchangeable input boards, this provides the ability to install whatever connection is required.
1080p or 1080i
We are often asked about the difference between the two.
The ‘resolution’ is one of the most defining features of a television set, primarily taken into consideration while making a purchase. It specifies the picture quality, clarity and degree of detailing that you can expect in the displayed picture. The next most important factor considered is the scanning technique used. While resolution decides the number of displayed pixels, the scanning technique decides in what manner the pixels are rendered. The two prime video mode choices, available to consumers when selecting a new television today are 1080i and 1080p, both offering 1920 x 1080 pixel resolution (assuming an aspect ratio of 16:9), but each uses a different scanning technique.
While planning a new television purchase, the resolution and scanning technology used, is pretty much the decider of overall viewing experience and the applications for which the TV could be used for. That’s why you are bound to be sucked up into a debate between 1080i and 1080p, that can only be ended with a straightforward comparison. 1080i and 1080p are two video mode technologies used by modern television manufacturers. Let me first define what the specifications of these video modes are and how they fundamentally differ in terms of intrinsic technology.
1080i Vs. 1080p – Comparison
Resolution in Pixels
1920 x 1080 1920 x 1080
(i = interlaced) Progressive Scanning
(p = progressive)
Displays 1080 lines in alternating
or interlacing fields
containing 540 lines each Displays 1080 lines sequentially
Over the Air Broadcasts,
Satellite HD Channels
CRT, HDTVs Modern HDTVs
LED, DLP TVs),
(Sony PlayStation 3,
Microsoft Xbox 360),
Satellite HD Channels,
* Needs Low Bandwidth * Sharper Picture
* Renders 3D Games,
High Motion Scenes Well
* No Distorting Visual Artifacts
* Interline Twitter Effects
* Needs High Refresh Rate * Needs High Bandwidth
Progressive scanning technology, as its name suggests, is far superior to the older interlaced scanning method. In progressive scanning, the video image is rendered by sequentially scanning 1080 lines within 1/24th of a second. Thus it renders 24 such frames per second to create the illusion of a moving image for our eyes. The keyword to be noted here is ‘Sequentially’. It renders the pixels one line after the other. 1080p is the modern HDTV standard. ‘Full HD’ refers to television sets that present video output with 1080p resolution. Most modern camcorders, cameras and smart phones (like Apple iPhone 5) provide 1080p video recording. Due to the high number of pixels transmitted per second, 1080p TVs require HDMI cables, that provide high bandwidth.
Older CRT monitors and TVs used ‘interlaced’ scanning while most modern LCD screen and TVs use the progressive scanning method. Interlacing displays two separate fields with odd and even lines that form the image, while the progressive scan displays lines serially, one by one. Within 1/30th of a second, first the field consisting of odd number lines is displayed, followed by even numbered lines.
Among the many advantages that progressive scan offers over interlaced scan, one lies in the fact that the picture it creates is less jittery and flickers less. It has no screen issues like ‘interline twitter’, which interlaced scanning is notorious for. It is the default standard used in HDTVs, LCD TVs and plasma TVs. It can display high motion images better than interlaced scanning. This is the main point of difference, when you debate which among 1080i or 1080p is better. Since progressive scanning provides the entire frame in one go, it renders a comparatively sharper image, with more detailing. This makes it ideal for rendering videos that involve rapidly changing visual frames like action movies or 3D games.
One thing to note is that no matter what kind of video content (1080i or p) is transmitted by a source device (like a satellite TV box or a gaming console like PS3) to a TV, it will only be rendered according to what scanning mode is functional in the television set. So if you use satellite television which transmits picture in 1080p, but you have a 1080i TV, the picture will be rendered in interlaced (1080i) scanning mode. In other words, the rendering and scanning technology used by your television is independent of video signal source.
Unlike CRT TVs, modern LED and LCD based HDTVs don’t use an electron beam to render the picture, which makes the term ‘scanning’, that refers to the travel of the beam, itself obsolete. These modern sets simply light up the appropriately positioned pixels on screen. Nevertheless, the differentiation between progressive and interlaced scanning still holds, with respect to the order in which the lines are rendered. All modern high-definition television sets use 1080p scanning by default. So the argument between the two scanning methods, as far as television sets are concerned today, is already largely unnecessary.
If you are planning to use your television for video editing or gaming, 1080p HDTV, with its progressive scanning technology is the one you opt for. Otherwise, the 1080i technology is good enough and can be purchased at a low cost. As it is, most modern television sets with the ‘Full HD’ epithet are 1080p. 1080p offers amazing picture clarity and makes for a good investment in the long run.