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Resolution Info

Overview:

Resolution is important when talking about TVs and Cable/Satellite channels, but can also be very confusing. One reason this is a confusing topic is because you have many TVs displaying at different resolutions, but TV channels displaying at just a few resolutions. Many people don’t know what the TV channels are displaying at, so they rely on the different resolution of TVs being sold. Most people just look for the highest resolution number and purchase that one. But that doesn’t necessary mean that it is the best. In the TV world the resolution that really matters is the number of horizontal lines of resolution. You might see resolutions that say 1280 x 768; the last number represents the horizontal lines across a TV. In that horizontal line there are thousands of pixels. Pixels are basically like a tiny flash light that can shine red, green, and blue, or all three colors. This article will discuss the different Resolution Technologies and what all the TVs and TV programs are displaying at.

What is Interlaced vs. Progressive and why is Progressive Better?

On Flat-panel TV sets you will notice they all have different resolutions. These resolutions can be: 1080p, 1080i, 720p, or 480p (this is just for ED TV’s see HD vs. ED for more info). The number stands for the amount of horizontal lines on a Television. The letter at the end of the number stands for the resolution type (“p” stands for Progressive Scan, “i” stands for Interlaced). Consequently, a number reading 1080i would stand for 1080 Horizontal Interlaced Lines of resolution.

What are Interlaced and Progressive? Interlaced is a way of displaying lines across a display, like a T.V. Even though some TV’s have 1080i (1080 interlaced lines) it’s really not better than 720p (720 progressive lines). Imagine you want to move a picture of a ball over a few inches. With Interlaced lines, 540 lines of the picture will be moved and then the rest of the 540 lines are moved in the next frame. This means that at any given time, only half of the picture is on the screen at a time. One frame will only display on the odd lines (1, 3, 5); the next frame will only display on the even lines (2, 4, 6). This happens so fast that the human eye is tricked into thinking that it is only seeing one picture. So if it takes 1/60th of a second to move the lines then your ball will get moved a few inches in 1/30th of a second. See the Example below:

Interlaced displays can cause flickering. Some people might not notice it, while others with sensitive eyes will. Most modern TVs are so fast you won’t be able to notice.

With Progressive, the image is moved progressively. This means that if a TV’s resolution is 720p (720 Progressive Horizontal Lines), all 720 lines are moved during each frame. See example below.

The result of progressive is a smoother picture. Instead of moving half the lines 4 inches and then the rest of the lines 4 inches as an Interlaced TV would do. Progressive, moves 720 lines (whole picture) 2 inches and then 2 inches. 720 lines of progressive would be like having 1440i Interlaced lines. As a simple rule you can take your Interlaced number and divide by 2. So for a 1080i line TV, you are actually getting 540 lines. With progressive you are getting your total horizontal lines used. Even 540 lines are good. Current DVDs display at 480p lines, but HDTV channels display at 720p lines or 1080i. As a general rule, try to stay away from Interlaced technology. However if the TV displays at 1080i or 720p then you are pretty much good to go. In recent technology advances there is media that will display at 1080p. Also HD Displays that are 1080p will not down convert the 1080i signal which will provide a better image then a 1080i channel on a 720p HD Display.