1080p, 720p, and 480p: What do they all mean? (HDTV tip)
Sep 29 at 07:26pm
With more major carriers offering unlimited data than ever before, the Big 4 have been forced to up the ante. That's why they're now offering high definition videos for unlimited streaming.
If you've ever watched a DVD, odds are you watched it in 480p video. This level of definition is referred to as DVD quality or standard quality. The HD category starts at almost twice that definition at 720p, known as semi-HD. Full HD is over twice that level of definition at 1080p resolution. It goes up yet another tier into anything over 1080p, which is "Ultra HD" or "4k."
If you're anything like most, this figures are just that - figures - with no real discernible meaning except some figures looking sharper and clearer than other figures. For most people, 480p, 780p, 1080p etc. are just letters and numbers. People understand that the higher ones equate to better videos, but they don't understand much more.
HD Streaming vs. SD Streaming Explained
Your television displays images by using pixels. Pixels are tiny dots that, together, form the cohesive picture you see on the screen. You can think of them as small, uniform puzzle or mosaic pieces that form a finished image when put together.
The "p" in "1080p" stands for "pixels," and 1080 is the number of pixels in the completed image. This is true for both pictures and videos. The higher the number of pixels, the clearer the image is. The number used in resolution nomenclature actually only refers to vertical pixels. For example, if a picture of video in 720p, there are 720 pixels going vertically but 1280 pixels going horizontally
Counting the lines
An old-school, garden-variety tube TV set can handle 480 lines of resolution from top to bottom, while the latest top-of-the-line 1080p HDTVs have a total of 1080 lines of vertical resolution.
In the middle, you’ll find 720p LCD and plasma HDTVs that have 720 lines, counting vertically.
Of course, a video image doesn’t just have vertical resolution; it has horizontal resolution, too. (This is where it gets a bit confusing, but bear with me.)
Most older tube TVs have a horizontal resolution of 640 lines, for a total resolution of 640 (across) by 480 (top to bottom), while most HDTV sets today have resolutions of either 1280 by 720 (for 720p sets) or 1920 by 1080 (for 1080p HDTVs).
What resolution is considered “HD,” then?
Conventional wisdom has it that any TV with a resolution of 1280 by 720—or 720p—and up counts as high definition. Anything less, and we’re talking SD (standard definition).
So while a 1080p HDTV has more than twice the total resolution of a 720p HDTV, both are still considered to be HDTV sets. And yes, you gusesed it: generally speaking, a 720p HDTV will be cheaper than an equivalent 1080p HD set.
Progressive vs. interlaced
When does the “p” in “1080p” or “720p” come into play? Well, the “p” stands for “progressive” video, in which every frame is “drawn” from top to bottom in a single pass, making for a smoother, more detailed image.
Meanwhile, you also have “interlaced” video, in which each frame is drawn in two passes—once for the odd lines, and a second time for the even lines.
But there’s a trade-off with interlaced video. Because the image is drawn in two separate passes, it tends to look … well, “jaggy” is one way of putting it. Progressive video, on the other hand, looks much smoother and solid. Think of the teeth of a comb; that’s how the image on interlaced video tends to look compared to the seamless edges of progressive video images.
So, why bother with “interlaced” video when progressive looks so much smoother and sharper? Because interlaced video can deliver the same size video image as progressive video does, but with only half the effort—a key factor when it came to yesterday’s television sets and relatively primitive broadcast technology.
An old tube TV from, say, forty years ago was probably a 480i set—only then, no one bothered to make the distinction between interlaced and progressive, namely because buying a progressive-scan TV (or an HDTV of any sort, for that matter) simply wasn’t an affordable option.
These days, even bargain TVs can handle video from progressive-scan DVD and Blu-ray players (which boast a standard, or “native,” resolution of 1080p) without breaking a sweat
Bottom line: While it’s nice to know that the “p” in “1080p” stands for, it’s beginning to matter less and less.