480i, 480p, 720p, 1080i and 1080p what does it all mean?
Standard TV from the days of black and white to the present color images we watch every day on television are made up of a series of still images displayed at 60 frames a second in the US and 50 frames a second in Europe. These still images consist of individual lines of information that move from left to right across the screen followed by more lines moving down the screen. With a Cathode Ray Tube (CRT) that most older TVs’ use for the display, the flat surface that you look at is coated on the inside with phosphor dots or rectangles. A beam of electrons is aimed at the dots or rectangles causing them to glow. With a standard definition TV there are 480 of these lines and 640 sets of dots or rectangles on each line. Each set of dots or rectangles consist of three color dots (Red Blue and Green) and the power or intensity of the electron beam determines how bright each color will be. There are actually three beams moving together across the face of the screen, each changing in intensity as they cross the phosphor dots or rectangles.
Interlaced (i) or Progressive (p)?
In order to reduce the bandwidth, normal TV signals only send 30/25 frames a second to the receiver made up of only 240 lines of information. If that were all we saw on the screen it would look like the old flickering movies. Within the TV set the signal is processed and sent twice to the CRT, the odd numbered lines are scanned and then the even numbered lines are scanned with the same image. This is referred to as an interlaced image and eliminates the flicker. However the true vertical resolution is only 240.
With a progressive image, 60/50 frames a second are sent to the receiver and all of the lines are scanned once for each frame and providing twice the detail as the interlaced image with the same screen. However this requires twice the bandwidth. Keep in mind that non-digital over the air is only 240 lines of original information, you can use a line doubler or scaler to increase the number of lines, but it will never be as sharp as the original image.
Horizontal resolution is much simpler, it is basically just the number of dots, rectangles or pixels across the width of your screen. For example standard definition TV is 640 X 480, the horizontal resolution is 640 for both interlaced and progressive.
Standard Definition DVD Full Screen and Wide screen
With the introduction of DVDs’ the horizontal resolution was increased from 640 to 720 to show the wider images of the original movies. Displays with a resolution of “720 X 480 ” could show these movies using the full screen width, however when viewing standard TV images, the people are slightly fatter.
Enhanced Definition TV
This format uses progressive scan and an even wider image for “854 X 480” and though is much better than standard TV it still does not come close to High Definition TV. Standard TV usually have a black bar on each side as the people would look weird being so fat.
720p High Definition TV
This format was a big step forward, however when viewing regular TV, you were still stuck back in the old format of “640 X 480”. 720P displays have a resolution of “1280 x 720” and use progressive scan for a very sharp image. Scalers and converters are used to boost the quality of the TV images to match the screen. For Analog signals, Component video equipment and cables are a minimum requirement. Video and S-Video will not work. The TV set may accept Video and S-Video, but will not take advantage of the full resolution, displaying a smaller image or through processing in the TV provide a larger image though not as sharp.
The Government steps in with 720p and 1080i high Definition TV Standards
On February 17, 2009, television stations will stop all analog broadcasts and only broadcast digitally. Older analog TVs will require converter boxes to receive over the air programming. Cable or satellite service will not be affected. There are two formats that will be used by the different stations.
The 720p format makes a picture with 720 vertical lines, each with 1280 pixels horizontally or a resolution of “1280 x 720”. 720p uses progressive scanning, like computers, which sends a complete picture 60 times per second. 720p provides the smoothest possible motion rendition, but it does not have as much resolution as 1080i.
The 1080i format makes a picture with 1080 vertical lines, each with 1920 pixels horizontally or a resolution of “1920 x 1080”. 1080i uses interlaced scanning, like traditional TV, which alternates sending odd lines and even lines and thus sends a complete picture 30 times per second. 1080i provides the highest possible resolution, but has the same motion rendition as traditional TV.
1080p High Definition DVD
Your next DVD player will most likely be able to play 50 Gbyte DVD’s that will use an High Definition Multimedia Interface (HDMI) that will also supply up to 7 channels of high definition audio along with the 1080p image. This is quickly becoming the standard for DVD movies in the same way that DVD replaced VCR tapes a few years ago.
To view these movies you will need an HDTV display with HDMI inputs and a DVD player capable of playing the new format with HDMI output. You will also need special HDMI cables to connect the two. Your cable or satellite provider will also use HDMI connections so you will need at least two HDMI connectors on your display device.
There are some drawbacks to the current models of High Definition DVD players. High- bandwidth Digital Content Protection (HDCP), creates a slow down when starting a movie, you may think that you have a problem with your DVD. The player is just talking to the display device to make sure that they are both licenced properly. Unless you are viewing the DVD on a 42 inch or larger screen you will have a hard time telling the difference between 720p and 1080p.
Broadband what does it mean?
You may be using broadband now and not even realize it. How often do you select an online movie from your local cable or dish company? Have you noticed how many high definition features are now being offered? As the selections become larger, watching streaming content will become so common that we will slowly forget about our DVD players. 720p is very common and soon 1080p will also be available. The protection for the movie producers is already there as the high definition boxes use HDMI with HDCP for the high definition outputs.
Organic Light Emitting Diode (OLED) TV’s
Then comes the OLED’s, we are already using them on the new cell phones and laptops. The first OLED television was introduced in 2008. As demand for larger displays increases and the pipeline that is now full of plasma and LCD screen began to empty we will hear more and more about the color quality of the OLED’s. For a few years the resolution of the displays will remain about the same and the sales pitch will be all about the colors. But keep in mind that there is no limit the size of the screen with OLED and it is also flexible. The flexibly will allow for easer handling and installation.
As the size of the screen increases a demand for greater resolution will start all over again. And with the flexibly comes the possibility of 360 degree wrap-a-round screens. Remember that the horizontal resolution is much easer obtain than the vertical so a resolution of 16000(or greater) X 1080p is not out of the question. 360 degree movies are not new, Disney World has had one in operation in Orlando for years. You stand in the center in a large group and turn around to follow the action. A few spinning recliners and the screen raised a few feet and away you go.