Home Theater Video

To make sure you buy the right display for your home theater, you need to understand your options and have a grasp of the specifics of TV and digital video media.

Broadcasting Basics

The images you see on a TV screen consist of a series of still images, or frames, that go by in quick succession—so quickly that they simulate motion. Each frame of video appears on the screen in horizontal lines. Lines can be scanned, or displayed, across the screen in one of two ways:

Interlaced scan: Lines are displayed in two repeating passes down the screen. The first pass displays all the odd-numbered lines from top to bottom; the second displays the even-numbered lines. Interlaced scan is represented by a lowercase i next to the TV’s resolution measurement (see “DTV (Digital TV) Standards” later in this section).
Progressive scan: All the lines of visual information on the screen are read consecutively in one pass, resulting in better image quality than in interlaced scan. Progressive scan is represented as a lowercase p next to the TV’s resolution measurement.

Resolution

The resolution of an image is the number of pixels per square inch that it contains. A pixel, short for “picture element,” is the smallest unit of an onscreen image. Essentially, it’s a digital dot made up of color and light. Because pixels are so tiny, it takes thousands or even millions of them clustered together to form the image that you see on your screen. Pixel density, also called native pixel resolution, screen resolution, native screen resolution, or pixels per inch (PPI), refers to the number of pixels in a square inch. The higher an image’s pixel density, the closer together the pixels and the sharper the image. Pixel density is represented as a ratio of the number of horizontal pixel rows to the number of vertical pixel columns. For example, a TV with a 1280 × 720 resolution will, in a given pass, show 1,280 pixels in a single row (i.e., the screen is 1,280 pixels wide) and 720 pixels in a single column (i.e., the screen is 720 pixels high).

DTV (Digital TV) Standards

There are three digital TV standards offering varying levels of picture quality: SDTV (standard-definition TV), EDTV (enhanced-definition TV), and HDTV (high-definition TV).

EDTV and SDTV have a higher resolution than old-fashioned analog TV, meaning that they display more lines of pixels on the screen, which results in better picture quality. HDTV has an even higher resolution than EDTV or SDTV.

SDTV: SDTV sets are listed as 480i, meaning 480 lines on the screen. The “i” refers to interlaced scan—480 lines of resolution are read in an alternating sequence (odd-numbered lines first, even-numbered second).
EDTV: EDTV sets are listed as 480p or 525p. The “p” refers to progressive scan—the 480 or 525 lines of resolution are read in one pass. EDTV sets can deliver HDTV broadcasting, whereas SDTVs cannot.
HDTV: HDTV offers the highest resolution of the three digital TV options. It’s close to the quality of 35mm film used in movie theaters. There are three HDTV standards:
- 720p: 720 lines are read progressively. 720 was the old standard for high definition.
- 1080i: 1080 lines are read interlaced. 1080 is the newest standard for high definition.
- 1080p: 1080 lines are read progressively. 1080p is the most detailed resolution currently available.
- The higher-end HD displays are capable of 1080p, meaning that they display 1,080 lines of resolution and refresh it progressively. These displays generally have higher price tags. The rest of the HD displays are 720p/1080i, meaning that they’ll support either of those HD resolutions.

HDTV vs. HDTV-Ready

When shopping around, you’ll encounter both HDTV sets and HDTV-ready sets.

HDTV sets: These TVs have built-in HDTV tuners (also called digital tuners or ATSC tuners) in addition to standard analog (NTSC) tuners. They can receive HDTV signals on their own—no extra equipment necessary.
HDTV-ready sets: Typically less expensive, these TVs must be connected to a separate, external HD tuner (you can buy one at an electronics store for about $100–200) in order to receive HDTV broadcasts.

Transition to All-Digital Television

Starting on February 17, 2009, analog signals will no longer be broadcast—all broadcasts will be digital. As a result, the Federal Communications Commission (FCC) has mandated that all TVs made as of March 1, 2007, must have built-in HDTV tuners. This doesn’t mean that analog-only TVs will become obsolete, though. You’ll just need to receive digital signals through a digital cable box or satellite box or buy a set-top digital-to-analog converter. This change won’t have much impact on your home theater system unless you’re using a display manufactured prior to March 1, 2007. All displays made after that date will already include the necessary equipment (a digital tuner) to handle the change.

TV Reception

To get the best possible reception, it’s necessary to hook up your home theater to a subscription television source. There are a few different types of cable television feeds:

Digital cable: This type of cable TV converts analog signals into digital ones. Rather than go from the cable wall outlet directly to the TV, it passes through a digital cable box that decodes information and passes it on to your TV, allowing hundreds of channels and additional features, such as on-demand programming.
CableCard: CableCard models itself after digital cable but eliminates the need for the digital cable box. Instead, you insert a small card into the CableCard slot and plug the coaxial cable into the TV. Using CableCard is often better than using a digital cable box because it eliminates rental fees and doesn’t hog the limited number of inputs on your TV or A/V receiver.But it’s also a relatively new technology, which has its downsides. These include not being able to receive an electronic programming guide or video-on-demand or Pay-Per-View services.
Satellite TV: This feed comes from a personal satellite dish, 18–24" in diameter, that’s mounted outside (usually on the roof) and then connected to a digital tuner box that can decode all the information from the satellite. Satellite TV includes thousands of channels and features.

Cost of Cable TV Service

Digital and satellite cable providers offer many different packages that vary in price. A basic package usually costs about $40 per month, whereas advanced packages cost upward of $120 per month.

High Definition and Cable TV

Not all cable programming is available in high definition (HD). As more television stations begin to offer HD programming, many others still do not. As with surround sound, HD signals have to be supplied by their source in order for your HD equipment to receive and display them. It’s possible, though, to receive HD channels over the air with an antenna only. The primary broadcast channels are distributed in HD, so a simple antenna can receive and display it as long as your HDTV has a built-in HD tuner and isn’t simply HD-ready (see “HDTV vs. HDTV-Ready” earlier in this section).

Shopping for a Video Display

The display is the part of the home theater that commands the most attention from the viewer. Today’s displays offer excellent picture quality and a wide range of screen sizes—in fact, screen sizes vary so greatly that the display is often the biggest variable in the cost of your home theater. Knowing which display suits your needs is an important step in building your home theater. The three main categories of displays are flat-panel, rear-projection, and front-projection.

Flat-Panel TVs

Flat-panel TVs offer superior image and sound quality in a package that’s lightweight and just a few inches thick. There are two types of flat-panel TVs:

LCD (liquid crystal display): These types of flat- panels are the most common type of display for home theater beginners, as they boast high quality and relatively low prices. LCD TVs, which range in size from 13–65", have screens that sandwich liquid crystals between two plates of glass. The crystals contain tiny cells, or pixels. When the pixels are charged by an electric current, they twist and untwist to allow or block light from a lamp located behind the screen, creating an image than tends to be brighter than those produced by plasma TVs.
Plasma: This technology was developed before LCD, so it’s a bit more advanced—consequently, plasmas are available in larger screen sizes. Ranging from 42" to a whopping 103", plasma TVs have screens made up of pixels that are filled with xenon and neon gas molecules and suspended between two panes of glass. When charged with an electric current, the gases turn into plasma (an ionized gas) and ignite phosphors to give off different colors of light, creating an image.

Rear-Projection TVs (RPTVs)

Rear-projection TVs (RPTVs) lack the svelte profile of flat-panels, but they offer similarly impressive image and sound quality at more affordable prices. In a traditional RPTV, the image fires from an internal projector and bounces off of an internal screen, reflecting onto the back of the screen on which it’s displayed. The latest RPTVs, though, use more advanced microdisplay technology. This internal technology uses tiny image chips, an illumination source, and an optics system to magnify the image onto screen sizes as large as 70" or more. The three types of microdisplay technologies are:

DLP: Short for digital light processing, this technology uses an optical semiconductor (called a DLP chip), which contains millions of microscopic mirrors that reflect light from an internal image source onto the back of the TV screen, producing a sharp picture with great contrast.
LCD: In LCD projection (which is different from LCD flat-panel technology), light passes through a silicone LCD chip that’s made up of pixels. The image is then magnified and reflects off an internal mirror and onto the screen.
LCoS: Short for liquid crystal on silicon, this technology combines the best of DLP and LCD: it uses liquid crystals (like LCD) to reflect light onto the screen (like DLP).

Front-Projection TVs

Front-projection TVs use an external projector to deliver the image onto a separate screen (or a wall, if you prefer). The latest projectors are sleek, compact devices that use one of two types of digital technology:

LCD: LCD panels are contained within the projector.
DLP: A DLP chip and millions of tiny mirrors are contained within the projector.

Display Pros and Cons

Type of Display	Pros	Cons
LCD (flat-panel)	Very thin Excellent picture quality Lightweight No burn-in (a network logo or other image that burns permanently into the screen)	Relatively narrow viewing angle Does not produce deep blacks Larger-size models are expensive
Plasma (flat-panel)	Very thin Available in larger sizes Excellent viewing angle Excellent picture quality	Susceptible to burn-in Tend to be the priciest of all display types Shorter life span compared to other display types
DLP (rear-projection)	Excellent picture quality Great contrast Crisp detail	Deeper cabinets than for flat-panels (though newer RPTV designs are slimmer) Requires darker rooms Narrow viewing angle
LCD (rear-projection)	Affordable Excellent blacks and shadow detail Uses special technology to prevent three-color “rainbow” effect	Limited contrast and black level Image may look slightly pixelated
LCoS (rear-projection)	Uses special technology to prevent three-color “rainbow” effect Images are crisp/nonpixelated Excellent contrast	Technology is new, so fewer models to choose from Internal lamp must be replaced frequently compared to other types of TVs
Front-projection	Bright Good picture and color quality Capable of very large images Hardware is small and easy to conceal	Requires specific lighting and a large room Needs special mounting Requires expensive bulb replacement No built-in TV tuner

TV Specifications

As you shop in stores or online for a display, you’ll notice that each one boasts specifications, or specs, that detail the display’s technical features. Specs are directly related to picture quality. The most important TV specifications are:

Size: Screen size is measured diagonally. Most flat-panel TVs range in size from 19–70". RPTVs are usually 37–70". Projectors can display images onto a separate screen that’s up to 100" in size.
Resolution: The resolution of a display refers to the clarity of its image. If you can afford it, get a display that’s capable of 1080p, the highest possible resolution. Otherwise, 720p/1080i is more than sufficient.
Contrast ratio: The contrast ratio measures the difference between the brightest white and the darkest black that a TV can produce. The ratio is presented as x,xxx:x. The first number in the ratio represents the brightness of the white, which can be 1,000 or higher, and the second number represents the brightness of the black, which is 1 in most cases. Average to lower-end displays have a contrast ratio of 1,000:1, whereas high-end displays have a contrast ratio of 10,000:1.
Aspect ratio: This spec determines whether the display has a traditional screen or a widescreen. 16:9 is the standard ratio for a widescreen display; 4:3 is the size of a traditional display. Content must be filmed in a 16:9 aspect ratio to be displayed properly on a widescreen (otherwise, you’ll see black bars to the left and right of the image). But a widescreen display can still show content filmed in 4:3 without stretching or distorting the picture.
Brightness: Brightness, which refers to the level of light that a front projector emits, is measured in lumens. The higher the lumen rating, the better the projector—1,000 lumens is a good starting point.
Viewing angle: An onscreen image can wash out and lose quality as you move to the side of the screen. Viewing angle is the maximum angle at which you can still see the screen’s image clearly. Most TVs today have viewing angles close to 175°.