What You Need To Know About Video Resolution

Where the eye meets the screen...

High-definition televisions in a row
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When you shop for a TV, Blu-ray Disc player, DVD player, or camcorder, your discussion with the salesperson always seems to touch a lot on factors revolving around resolution. It's lines this and pixels that and so forth... After a while, none of it seems to make sense. In the following article, I shed some light on this topic, hopefully making the nature of video resolution more understandable.

The Basics of Video Resolution

A television or recorded video image is basically made up of scan lines.

Unlike film, in which the whole image is projected on a screen at once, a video image is composed of rapidly scanning lines across a screen starting at the top of the screen and moving to the bottom. These lines can be displayed in two ways. The first way is to split the lines into two fields in which all of the odd numbered lines are displayed first and then all of the even numbered lines are displayed next, in essence, producing a complete frame. This process is called interlacing or interlaced scan.

The second method, used in digital video recording, digital TVs, and computer monitors, is referred to as a progressive scan. Instead of displaying the lines in two alternate fields, progressive scan allows the lines to displayed sequentially. This means that both the odd and even numbered lines are displayed in numerical sequence.

Analog Video: NTSC/PAL/SECAM

The number of vertical scan lines dictates the capability to produce a detailed image, but there is more.

It is obvious at this point that the larger the number of vertical scan lines, the more detailed the image. However, within the current arena of video, the number of vertical scan lines is fixed within a system. The current analog video systems are NTSC, PAL, and SECAM.

NTSC is based on a 525-line, 60 fields/30 frames-per-second, at the 60Hz system for transmission and display of video images.

This is an interlaced system in which each frame is scanned in two fields of 262 lines, which is then combined to display a frame of video with 525 scan lines. NTSC is the official analog video standard in the U.S., Canada, Mexico, some parts of Central and South America, Japan, Taiwan, and Korea.

PAL is the dominant format in the World for analog television broadcasting and video display and is based on a 625 line, 50 field/25 frames a second, 50HZ system. The signal is interlaced, like NTSC into two fields, composed of 312 lines each. Several distinguishing features are one: a better overall picture than NTSC because of the increased amount of scan lines. Two: since color was part of the standard from the beginning, color consistency between stations and TVs are much better. There is a downside to PAL, however since there are fewer frames (25) displayed per second, sometimes you can notice a slight flicker in the image, much like the flicker seen on projected film. Countries on the PAL system include the U.K., Germany, Spain, Portugal, Italy, China, India, most of Africa, and the Middle East.

SECAM is the "outlaw" of analog video standards. Like PAL, it is a 625 line, 50 field/25 frames per second interlaced system, but the color component is implemented differently than in either PAL or NTSC.

Countries on the SECAM system include France, Russia, Eastern Europe, and some parts of the Middle East.

The number of scan lines, or vertical resolution, of NTSC/PAL/SECAM are constant in that all analog video recording and display equipment conforms to the above standards. However, in addition to vertical scan lines, the amount of dots displayed within each line on the screen contributes to a factor known as horizontal resolution which can vary depending on both the ability of a video recording/playback device to record the dots and the ability of a video monitor to display dots on a screen.

While the number of vertical scan lines within a video system(NTSC/PAL/SECAM) is fixed, the number of dots displayed within each line can vary according to the input source or the ability of the TV monitor itself. This is often referred to as horizontal resolution and is expressed in terms of the lines that the dots create as they are displayed across the screen from left to right.

Using NTSC as an example, there are 525 scan lines (vertical resolution) total, but only 485 scan lines are used to comprise the basic detail in the image (the remaining lines are encoded with other information, such as closed captioning and other technical information). Most analog TVs with at least composite AV inputs can display up to 450 lines of horizontal resolution, with higher-end monitors capable of much more.

The following is a list of input sources and their approximate horizontal resolution capability. Some variations listed are due to the range of quality of different brands and models of products using each format.

Video format with horizontal resolution estimates:

220 - 240 lines

250 lines

250 - 280 lines

270 - 280 lines

Analog TV Broadcast
330 lines

Analog Cable TV
330 lines

Standard Digital Cable
330 - 500 lines (Depends on original source of the signal and compression used in downloading to the cable box)

400 lines

250 - 400+ lines (Depends on recording mode and compression used)

400 - 425 lines

380 - 440 lines

Digital 8
400 - 500 lines

400 - 520 lines

500 lines

500 lines

Commercial DVD
Up to 540 lines

As you can see, there is quite a difference in the detail that different video formats can input into a TV or video display. Basically, VHS is on the bottom end of things, while miniDV and DVD represent the best that analog video can currently produce in terms of detail.

However, another factor that has to be considered is how the resolution is stated for Digital and HDTV.

In the previous two pages, I outlined the basics of analog video resolution. However, with the advent of DTV and HDTV, video resolution has become more confusing.

Just as in analog video there is both a vertical and horizontal component to digital video resolution. However, the total image resolution displayed in DTV and HDTV is referred to in terms of the number of pixels on the screen rather than lines. I will get back to that point shortly.

Digital TV Resolution Standards

In current digital TV standards, there are a total of 18 video scan rates that are approved by the FCC for use in the U.S. system. Fortunately, for the consumer, and for this Guide, there are only three that are commonly used. The three vertical scan line systems used in digital TV are 480p (480 lines vertically scanned in a progressive fashion), 720p (720 lines vertically scanned in a progressive fashion), and 1080i (1,080 lines scanned in an interlaced fashion).

Based on vertical scan rates, digital TV has much more capacity for a finer detailed image than that of analog TV.

However, In order to display the raw scan lines, a video monitor has to be able to reproduce the full detail of the incoming DTV or HDTV program material. In addition, true HDTV is also dependent on a monitor that displays the image in a 16x9 screen shape. However, there are also HDTV monitors in the traditional 4x3 shape, in which case a 16x9 image is displayed in a letterbox format, with black lines on the top and bottom of the screen. Another factor on how a digital TV image is displayed is the actual size of the screen. Basically, you can fit more dots on a 50-inch Plasma Screen than a 27-inch Direct View DTV.


So, even though you may be inputting a 1080i image into your HDTV, your TV may not have the ability to reproduce all the dots within those lines. In this case, the signal is often reprocessed (upconverted or downconverted) to conform to the number and size of dots (pixels) on the physical screen. At full resolution on a 16x9 screen, a 1080i image is comprised of 1920x1080 pixels (about a two-megapixel field).

However, if your monitor is not capable of reproducing the total pixel field, then the image is scaled to fit the number of pixels in the display monitor's pixel field. So, an HDTV image of 1920x1080 can be scaled to fit 1366x768, 1280x720, 1024x768, 852x480, or other pixel field. The relative loss of detail actually experienced by the viewer will depend on factors such as screen size and viewing distance from the screen.

In essence, when purchasing an HDTV, it is not only important to make sure that you can input 480p, 720p, or 1080i signals, but you must also consider the pixel field of the monitor itself (and whether upconversion/downconversion is used).

To go into further detail on this, televisions that have to downconvert an HDTV signal (such as 720p, 1080i, or 1080p) to a pixel field of 852x480 (480p) for example, are referred to as EDTVs and not HDTVs. EDTV stands for Enhanced Definition Television.

EDTV Video Projection

In addition to EDTV TVs, some budget-priced video projectors are capable only of EDTV resolution and are not capable of projecting a true HDTV-resolution image. Just as with EDTVs, these video projectors will often have the capability of inputting an HDTV signal through HD-component, DVI, or HDMI input connections. However, if the projector has a native pixel resolution of 1024x768, the video projector will have to scale a 1080p, 1080i, or 720p HD image down to fit its lower native pixel resolution, in order to project it onto the screen.

Resolution Requirement For True HD Image Display

On the other hand, if a TV or video projector has a native display resolution of 720p, they are referred to as meeting HDTV specs. Most LCD and Plasma TVs, for example, currently have a native display resolution of 1080p. So, when faced with a 480i/p, 720p, or 1080i input signal, the TV will scale the signal to 1080p to display it on the screen. If a TV or video projector has a native display resolution of 720p or higher, it definitely has true HDTV resolution capability.


1080p represents 1,080 lines of resolution scanned sequentially. In other words, all lines are scanned in progressively, providing the most detailed high-definition video image that is currently available to consumers.

Access to 1080p is determined by whether your HDTV has the ability to access a 1080p signal from a source directly, or your HDTV has to scale and process all signal inputs to 1080p internally.

1080p/60 vs 1080p/24

Almost all HDTVs that accept a 1080p input signal directly accept what is known as 1080p/60. 1080p/60 represents a 1080p signal transferred and displayed at a rate of 60 frames-per-second (30 frames displayed twice per second). This is a standard progressive scan 1920x1080 pixel video signal.

However, with the advent of Blu-ray Disc and HD-DVD, a variation of 1080p is being promoted and implemented: 1080p/24. What 1080p/24 represents is the frame rate of standard 35mm film transferred directly in its native 24 frames-per-second from a source (such as a film on a Blu-ray or HD-DVD disc). This means that in order to display this image on an HDTV, the HDTV has to have the ability to display 1080p resolution at 24 frames per second.

Up to this point, most Blu-ray Disc and HD-DVD players read the 1080p/24 format information off of the disc and then reprocesses it so that it will be able to output the signal as 1080p/60, thus making it compatible with most 1080p input compatible HDTVs.

However, most Blu-ray Disc players can also output 1080p/24 off the disc directly and send that signal unchanged to an HDTV. In this case, if the HDTV cannot process or display the 1080p/24 signal directly, the Blu-ray Disc player will then reprocess the 1080p/24 signal to 1080p/60 so that the HDTV will recognize the signal.

DVD Resolution Upscaling

Although standard DVD is not a high-resolution format, most DVD players now have the ability to output a video signal in the 720p, 1080i, or 1080p format allows the DVD player's video output to more closely match the capabilities of today's HDTVs.

Although upscaling standard DVDs is not the same as watching DVDs in true, high definition, as current DVDs are not recorded in high definition, you will experience increased detail and color you didn't think was possible from a DVD player. Blu-ray Discs and HD-DVDs are the only true source of full 1080p high-definition video in a disc-based format.

Video upscaling works best on fixed pixel displays, such as LCD or Plasma sets, the upscaling may result in harsh images on standard CRT and CRT-based Projection sets. In addition, if your television has a native display resolution other than 720p, 1080i, or 1080p, the TVs video processor will rescale the incoming signal to its own specification, which can also yield different results on the final, displayed television image.

For additional details on DVD upscaling check out my articles: What is Meant by an HD-Compatible DVD Player? and DVD Video Upscaling.

Don't Get Confused

If you are still a little confused, you are not alone. Remember, video resolution can be stated either in lines or pixels. However, don't get caught up in all the video resolution numbers. Look at it this way, VHS looks great on a 13-inch TV, but "crappy" on a big screen.

In addition, the resolution isn't the only factor that contributes to a good TV image. Factors such as color accuracy, contrast ratio, brightness, maximum viewing angle, and whether the image is interlaced or progressive, all contribute to the quality of the picture.

You can have a very detailed image, but if the other factors mentioned aren't sufficiently present, you have a lousy TV. Even the best TVs can't make a poor import source look good. In fact, ordinary broadcast TV (with its low resolution) sometimes looks worse on an HDTV that it does on a good, standard, analog set.

For an additional look at high definition resolution that may help in your next TV purchase, check out the article from About.com's site for TV/Video: Which HDTV Should You Buy: 720p, 1080i, 1080p?.


In conclusion, this article was intended to provide an overview of the basic principles regarding video resolution. This was not intended to be a technical dissertation and more detailed, related points were not elaborated. However, for those that wish to dig deeper into high definition video resolution, check out the following articles:

1080p Facts

1080i vs 1080p

720p vs 1080i

720p vs 1080p

4K Resolution

8K Resolution

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