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How Does Digital Video Work?

We learned in skule how a TV set works: a flying beam rasters down the screen, energizing phosphors on the back of the glass; different phosphors for different colors; higher energy beam for brighter spots... Where could I find an explanation at roughly this level of generality of how video cards and digital "screens" work? How does a photograph, or a data-base of X-million numerical values, get turned into a picture on a plasma screen? A Jumbotron? The outside of the NASDAQ building in Times Square? I've Googled like crazy around this question, but end up swamped with stuff about what is the best video card for your gaming fun. "How-to" searches get me how to put in a video card. Still, Google pointers would be handy. TIA, -dlj.

Reply to
David Lloyd-Jones
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I don't know quite what level of detail you want, but there are any number of texts that cover the operation of the various non-CRT display technologies (few of which, by the way, are truly "digital" - LCDs AREN'T, for instance). I could even, at the risk of putting in a plug here, point you to my own book:

Display Interfaces: Fundamentals and Standards

... published as part of the SID/Wiley Display Technology series by John Wiley & Sons. But there are certainly a lot of other sources, too.

Bob M.

Reply to
Bob Myers

Did you try here? There may be something...

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Tom

Reply to
Tom MacIntyre

Where are you from? Do they teach conventional English spelling?

Reply to
Richard Crowley

---------------------- A video card is a bank of RAM that is dual-port, it can be read from and written to at the same time, or just RAM that can be written to and read from alternately fast enough, to be used by a video generator chip, or a set of counters and logic, to assemble the typical NTSC or other kinds of video streams and route them to one or several outputs for multiple colors.

------------------------- The general process is the similar raster process, you scan a pixel and then a line at a time, using decoder/demultiplexers and counters.

A photo gets digitized by sensing color and intensity in a region and then approximating it as a single pixel of a specific intensity and color balance of red, green and blue. The multi-CRT over-large TV "walls" use counters to count pixels and lines, and arrange to extraploate/interpolate pixel reductions or expansions, often using dithering and other focal info-tricks and route them to the correct new re-assembled video to each separate monitor.

The purely pixel-field digital screens use a memory "backing" for the emitter plane, and it writes to that memory to refresh to the new image, some schemes blank it, some do not, or use more bit-tricks to avoid ripple and aliasing.

Scrolling signs are merely demuxed addressing with latches or shift-registers feeding LEDs

-Steve

--
-Steve Walz  rstevew@armory.com   ftp://ftp.armory.com/pub/user/rstevew
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Reply to
R. Steve Walz

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Reply to
H. Dziardziel

Ah yes skule. I remumble it woll.

Reply to
CWatters

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