Getting the Details on Resolution - dummies

By Danny Briere, Pat Hurley

A video display’s resolution measures the picture’s precision and sharpness, based on the pixels or lines of resolution available on the screen. The resolution specs are most important for HDTV sources (and even widescreen anamorphic DVDs).

For standard-definition programming — such as NTSC television and, to a degree, DVD —resolution isn’t a huge deal. Any display can handle the 480 vertical lines of resolution of these formats — which is not to say they’ll all look the same!

When you look at specs for a particular display, you might see resolution discussed in two related but different ways:

  • Display resolution: Also called a display’s native resolution, this is simply the number of pixels or lines of resolution that the display has on its screen. Most digital TVs have a fixed display resolution — meaning that they are physically built with a certain number of pixels and anything they display on the screen will consist of that number of pixels, regardless of the resolution of the video signal going into the display. Display resolution is what it says it is — the measure of your display’s resolution.

  • Input resolutions: Different video sources, such as analog TV, DVDs, and high-definition TV (HDTV) signals, have their own resolution. For example, HDTV signals have 720 or 1080 lines of resolution, and analog TV signals have 480 lines. A display’s input resolutions are simply the resolutions of the video signals that the TV can accept and display. Read the fine print closely — some displays can accept high-definition resolutions but display it at a lower (not high-definition) resolution.

    As an example, a specific high-definition display may have a display resolution of 720 lines and be able to accept inputs of 480, 720, and 1,080 lines of resolution — but will display the 1080 signal at the lower 720 resolution.

Display vendors generally focus on the vertical resolution of their sets, which corresponds to the most commonly discussed resolutions of HDTV: 720 and 1080. Some displays (particularly those that have a fixed-pixel system, such as LCD or plasma) give resolution in terms of both horizontal and vertical numbers — similar to the way resolutions are discussed in the computer display world. So, you might see a plasma display with a resolution of 1280 x 720p (which corresponds to 720p). In this case, the 1280 refers to the horizontal resolution (the number of pixels, or individual points, across the screen) and 720 refers to the vertical number (like the scan lines on a conventional TV).

When you get into high-definition digital displays, you’ll find out that your display holds some circuitry that handles this conversion from input resolution to display resolution. This circuitry is known as the scaler because it scales the image from one size to another. When you’re reading reviews of different displays that you are considering, pay close attention to the capabilities of this scaler; it will manipulate most of the video signals you send into your TV. All else being equal, a display with a better scaler will have a better picture, especially when it displays video sources that aren’t created in the display’s native display resolution.