What makes high def, high def

[Audionut]

Hi, I'm trying to explain to someone what makes video high definition. For the life of me I can't seen to get it across. I was hoping that a few of you guys could explain it for me. Then I could point him to this thread. TIA.

[communist]

Its all about the resolution (and FPS):
Standard Definition = 720x576px (PAL) or 720x480px (NTSC)
High Definition = 1280x720px or higher.

Now just upscaling SD to a bigger resolution just wont make it HD - though if you go by the definition of just looking at the resolution this would count as HD too.
*Real* HD has to be acquired and processed and delivered in HD Imho.
That means using a camera that can actually capture at least 1280x720px (no upscaling), then process and transmit it at the appropriate res and also displaying it at 1280x720px or higher.

You'll find that a lot of consumer grade *HD* cameras use CCDs or CMOS chips that can only capture 1000x1080px (rough guess) and the rest is interpolated. Its a bit muddy at that point ;)

[500 Kip]

http://en.wikipedia.org/wiki/High-definition_video

[jeffy]

The resolution of the source and the resolution of the display device (when presenting it in full clarity):

Image resolution, the level of detail of an image
http://en.wikipedia.org/wiki/Image_resolution

Display resolution, the level of detail on a display device, such as a monitor
http://en.wikipedia.org/wiki/Display_resolution

[Audionut]

Everything else such as whether it's been upscaled etc only affects quality.

[Brother John]

HD might mean a couple of things.
Broadly defined as »more resolution than we used to have previously«.
Referring to the current HD industry standard, i.e. 1280×720 or 1920×1080 resolution.
Broadly defined as »great quality«. Though this is more often called HQ (High Quality) and not necessarily connected to high resolution.
I’d say the industry definition is the most commonly used one.

And then of course you can get into the gory details around upscaling, compression artefacts etc. Technically, if you resize VCD to 1920×1080 it is an HD resolution. But is it HD? It’s certainly not HQ. :p

[mpiper]

Here is what I say to explain HD to a non-tech person. Most people are familiar enough with Digital cameras to get it.
Standard TV, or Standard Definition is only 720X480, which if it was a digital photo, is only a .3 Megapixel image. Not even half a megapixel!
BUT, HD is 1920 X1080, which is the same as a 2.1 Megapixel camera! So HD has almost 10 times the detail of SD.

When they ask what good the detail is, I have said:
I watched The Bourne supremacy on DVD. There is this scene where the team trying to find bourne is in a room full of computers. You can see text and pictures, but it's too small. When I watched it in HD, I could read everything on the computer monitor! The difference between DVD and HD is like watching a home recording of a TV show on VHS tape and watching the same show on a DVD, only better! Or watching a football game from the nosebleeds on the opposing side's goal versus the first row on the 50 yard line.

None of this is terribly technical, and it basically avoids the actual definition, but every single person I have talked to has made a trip to Best Buy the next day JUST to see an example, and the next time I see them, they rave about how sharp everything was. I sold 5 people on HD-DVD by doinhg that, and 2 people on Bluray, even though I was pushing HD-DVD (Yeah, I know. Wrong side. I now have 35 movies that will be the 45s of tomorrow. {45s - little single song records. . . Made of vinyl. . . Before they invented CDs. . . Even older than cassettes. . . Uh, cassettes were these little plastic rectangles that had spools of magnetic tape that. . .oh, never mind. . . :( } )

[DigitAl56K]

Here is what I say to explain HD to a non-tech person. Most people are familiar enough with Digital cameras to get it.
Standard TV, or Standard Definition is only 720X480, which if it was a digital photo, is only a .3 Megapixel image. Not even half a megapixel!
BUT, HD is 1920 X1080, which is the same as a 2.1 Megapixel camera! So HD has almost 10 times the detail of SD.

(720x480) / (1920x1080) = 6 times the resolution, a little less if you're coming from PAL.

With regards to it being "all about the resolution", mmh, I'd say no. Is HD really HD if you're watching 1920x1080 pixels of blurry, smudgy crap because some guy at the network decided they didn't want to waste too much bandwidth on the channel you're watching? Is HD really HD if you're getting low quality audio full of artifacts? Is HD really HD if frames are dropping left, right, and center?

To me, HD is better defined as a combination of:

1280x720 pixels or greater in one or more dimensions
High bitrate audio, I don't mind if it's only stereo most of the time, but it has to approximate CD quality or better.
No obvious blocking, blurring, motion residuals
Reasonable texture definition
A fairly sharp picture
Smooth playback at 24fps or better
Good color definition and contrast
Butterscotch popcorn and a super-sized soda


.. okay okay maybe not that last one. Not all of the factors are perfectly measurable, but I would not call everything marketed as HD "high definition" (http://gizmodo.com/374193/comcast-compressing-hdtv-signals-to-fit-three-shows-into-two-shows-bandwidth). "HD" should imply a certain standard of experience beyond the associated technicalities.