HDTV – What is it?
High-definition television, or HDTV, is a new way of broadcasting TV programs that is far superior to “regular” TV in both picture and sound. Why the difference?
- High-definition (HD) broadcasts use a digital signal, while the standard TV signals you’ve been watching for years are analog. Digitals signals can support a higher resolution. HDTVs have resolutions of 1280x720 pixels or better.
- HD broadcasts support 5.1 channel Dolby Digital surround sound, which is similar to the sound you hear in movie theatres. You may already have a TV that offers surround sound. However, you probably only experience true surround sound when you watch DVDs and videos – not when you’re watching broadcast TV. HD broadcasts feature true surround sound. That means you can enjoy true surround sound with your favorite TV programs in addition to DVDs and videos.
An integrated HDTVhas a built-in digital ATSC tuner and has resolution of 720p or higher. Since 2007, the majority of new televisions sold have been HDTVs. That is because beginning March 1, 2007, all television reception devices imported into the U.S. or shipped via interstate commerce must contain a digital tuner. Thus, all new TVs sold by retailers should be equipped with a digital tuner. Nearly all also have HD quality resolution, deeming most new TVs to be HDTVs. To receive and display any free and available over-the-air HD broadcasts on your HDTV, all you need to do is purchase an HD antenna. Or you can simply plug into your existing digital cable or satellite set-top box; however, some carriers may charge extra for an HD-compatible set-top box or require you to subscribe to additional programming to receive HD broadcasts.
Contrast Ratio - This refers to the difference between the brightest whites and the darkest blacks a TV can display. The key thing to consider is how “black” your blacks will be. A higher contrast ratio means a deeper black. In addition, a higher contrast ratio also means you can have more ambient light in the room without washing out the on-screen color. As of 2006, contrast ratios range from 300:1 to 5000:1 for home theatre projectors to 10,000:1 on high-end plasma and LCD TVs.
Frame rate – A TV’s frame rate describes how many times it makes a complete picture on the screen every second. Again, the higher the number, the faster images are processed. This makes a difference when watching fast-moving action or playing fast-paced video games with lots of action. The two most common numbers you’ll see are 720p and 1080i.
What do the “I” and “p” mean? The “I” indicates that the TV draws images using an interlaced method. The “p” indicates that the TV draws images using a progressive scan method. In general, progressive scan renders images faster and produces a more detailed, film-like image.
HDMI – High-Definition Multimedia Interface, or HDMI, is a new type of connector cable that carries both all-digital audio and video signals over a single cable, eliminating the need for separate cables to connect your audio and video components. No more tangled mess of cables! In addition, HDMI cables deliver the best possible digital quality signals for both audio and video.
Response Time - This refers to the time it takes a pixel to change state from black-to-white-to-black again. In general, the faster the response time, the better the picture, especially when viewing fast action in movies, sports, and video games. Plasma and CRT televisions have virtually instantaneous response time, while LCD models tend to be a bit slower. The slower response time can result in what is referred to as “image lag” or a slight blurring of fast-moving images. As of 2007, a “fast” response time is considered to be anywhere from 8msec to 3msec.
Q. What different types of HDTVs are available and how do they compare to one another?
A. Rear Projection DLP, and Flat Panel LCD, Plasma and LED have their pros and cons.
Rear Projection (DLP)
Good to excellent picture quality
Sizes from 40" to 73"
Generally less expensive than flat panel TVs
Bigger, heavier, bulkier than LCD and plasma models
Flat Panel LCD
Excellent picture quality
Available in small screen sizes (under 32")
Can double as computer monitor
Generally less expensive than plasma
Relatively narrow viewing angle
Pixel response can be slow, causing blurred motion, particularly when using the screen for video gaming or other high-demand activities
Flat Panel Plasma
Superior picture quality to LCD, though it is debatable
Screen sizes up to 70" or more
Wide viewing angle; looks good from almost any angle
Faster pixel response; better for gaming and fast action sports
Generally more expensive than LCD
Slight risk of "burn-in", in which a static image becomes "burned" into the screen permanently
Q. What type of TVs use a lamp?
A. Rear Projection DLP TVs use a lamp, with the typical lamp life ranging from 5,000 to 8,000 hours. With normal use, that translates to many years of TV viewing. You may never need to replace your DLP TV lamp (depending on how long you own the TV), but if you do, the typical replacement lamp costs around $200.
Q. What is screen resolution?
A. Resolution refers to the number of pixels being used to project an image. In general, the larger the numbers the better the resolution and the picture quality. Current HD programming tops out at 1920 x 1080 pixels. In fact, HD is generally about six times sharper than standard TV, and can be as much as ten times greater.
Q. What's the difference between 720p, 1080p, and 1080i?
A. 720 and 1080 refer to horizontal pixel counts. Both 1080p and 1080i HD broadcasts offer higher resolution than 720p broadcasts. The "i" indicates that the TV draws images using an interlaced method. The "p" indicates that the TV draws images using a progressive scan method. In general, progressive scan renders images faster and produces a more detailed, more film-like image. This means 1080p offers the highest quality currently available.
Q. What do the "i" and "p" mean?
A. The letters "p" and "i" indicate the picture-scanning method - progressive or interlaced. In interlaced scanning, the on-screen image is created in two split-second passes, drawing all the odd-numbered lines first then going back to fill in all the even-numbered lines. In contrast, progressive scanning draws each frame sequentially in a single pass to create a smoother, cleaner picture. So, progressive scanning is theoretically better than interlaced scanning.
Q. What do I need to watch HD broadcasts?
A. Your choices for watching HDTV are via over-the-air broadcasts, cable or digital satellite.
HDTV (ATSC / digital) tuner - separate unit or built into TV
Indoor or outdoor UHF or UHF/VHF antenna
Local HDTV broadcasts (free)
HD-compatible cable box (or TV with built-in digital cable tuner: QAM or CableCARD-ready)
HD programming (subscription required)
Digital Satellite HDTV
HD-compatible satellite receiver
HD-compatible satellite dish
HD programming (subscription required)
Q. What's the difference between a "3D-ready" and a "3D-capable" TV?
A. 3D-ready TVs come with the necessary emitter built-in; 3D-capable TVs do not, so you'll need to add on a separate one for 3D-capable TVs.
Q. What do I need to watch 3DTV at home?
A. You'll need a TV labeled "3D-ready" or "3D-capable", a pair of 3D glasses for each person watching, and a 3D video source such as a 3D Blu-ray movie.