SD - what do these letters stand for?

[gateway2k]

I keep reading SD this , SD that...
What does it stand for?

Sorry for being stupid

[GAmbrose]

Standard Definition.

Gary A

[MichielO]

SD=Standard Definition, HD=High Definition
SD has a resolution of 852x480 pixels, where HD has mostly 1024x768 (42 inch) or 1366x768 (50 inch). Or more...

[AndrewTheMuppet]

There's actually 3 main definition types...
SD - 720x480 - this is the resolution of current analogue broadcasts.
ED - 852x480 - this is enhanced definition and is the native resolution of most non-HD plasmas. ( they scale the SD broadcasts up ).
HD - 1280x720, 1920x1080. (future Sky & BBC HD broadcasts will be at these resolutions)

[StooMonster]

Region 2 ("PAL") DVDs and Sky and Freeview are 720x576 pixels, Region 1 ("NTSC") DVDs are 720x480 pixels. Both of these are 'SD'.

In British television SD is 576 rows, whereas American SD is 480 rows.

Some plasmas refer to themselves as being SD, but they mean in the American sense. i.e. they have 480 rows of pixels. This means that to display British television pictures they have to downscale the picture and ignor 20% of the picture information.

HD are typically displays with more than 720 rows of pixels.

StooMonster

'they have to downscale the picture and ignor 20% of the picture information'

that's not quite true.
A PAL broadcast is interlaced (288 lines frame), where as an ED plasma is progressive 480 lines /frame. This more than makes up for the so called 'lost' 96 interlaced lines

[chedmaster]

Originally Posted by MAT365

'they have to downscale the picture and ignor 20% of the picture information'

that's not quite true.
A PAL broadcast is interlaced (288 lines frame), where as an ED plasma is progressive 480 lines /frame. This more than makes up for the so called 'lost' 96 interlaced lines

depends how clever the de-interlacing and scaling is

yes I was being slightly pedantic.
If you compare a ED plasma running PAL with a good 100Hz CRT with high performance DSP you might see a difference.

I can appreciate why ED (which most SD plasma's actually are) is not pushed as a feature in PAL countries, but on the other end of the scale it's a non argument on the vertical resolution of Plasma/480p vs CRT/576i.

[StooMonster]

Originally Posted by MAT365

that's not quite true.
A PAL broadcast is interlaced (288 lines frame), where as an ED plasma is progressive 480 lines /frame. This more than makes up for the so called 'lost' 96 interlaced lines

Err... that's not true.

Any deinterlacer, be it built into the screen or DVD player or scaler will render 576 rows of pixels for PAL. Scaling this down to 480 rows loses 20% of the picture information. It is a simple fact.

StooMonster

[symphara]

Originally Posted by MAT365

'they have to downscale the picture and ignor 20% of the picture information'

that's not quite true.
A PAL broadcast is interlaced (288 lines frame), where as an ED plasma is progressive 480 lines /frame. This more than makes up for the so called 'lost' 96 interlaced lines

There are many PAL DVDs using 720x576 progressive, not that it would make up for the resolution loss anyway. This reminds me of the argument that 720p is somehow better than 1080i, because the stream has more data!

</symphara>

yes that's right your DVD will achieve this :
assuming

1. it is set to progressive scan
2. Set to PAL output
3. playing a PAL DVD.

But for all other sources (which is likely to be 80% of viewing for most people) e.g sky, cable etc you still only get 288 visible lines/frame (50Hz)
Human perception subsequently integrates this down to a resolution well below 576 lines at 25Hz.

[symphara]

Originally Posted by MAT365

yes that's right your DVD will achieve this :
assuming

1. it is set to progressive scan
2. Set to PAL output
3. playing a PAL DVD.

But for all other sources (which is likely to be 80% of viewing for most people) e.g sky, cable etc you still only get 288 visible lines/frame (50Hz)
Human perception subsequently integrates this down to a resolution well below 576 lines at 25Hz.

Why would it be well below 576 lines, at 25Hz? Sending 576 lines at 50Hz, after de-interlacing, will give exactly 576 lines, at 25Hz. And it's not human perception doing that - it's the electronics in the panel (which is a progressive scan display).

</symphara>

[StooMonster]

Originally Posted by MAT365

But for all other sources (which is likely to be 80% of viewing for most people) e.g sky, cable etc you still only get 288 visible lines/frame (50Hz)
Human perception subsequently integrates this down to a resolution well below 576 lines at 25Hz.

What you are talking about is interlaced CRT. This is the plasma forum, all plasma displays (except ALiS ones) are progressive.

If not done by the source (e.g. Sky or DVD), or external video processor (e.g. scaler), deinterlacing will be done by the screen before it scales the image to native resolution size.

All film based sources (e.g. all American drama series, and all movies) will have 2:2 pulldown applied and "weaving" deinterlacing will combine the two fields to create one frame. This frame is a complete 720x576 pixel picture that will be displayed at 25 frames per second, but repeated twice to make 50Hz. This 720x576 frame will be upscaled horizontally and downscaled vertically.

All video based sources (e.g. news, sports, studio based programmes) will be deinterlaced using "bob" or "interpolate" to mix 50 fields per second to create complete 720x576 pixel pictures that will be displayed at 50 frames per second. This 720x576 frame will be upscaled horizontally and downscaled vertically.

What deinterlacers do not do is stretch 288 rows of pixels over 480 rows at 50Hz.

480 row plasmas were designed for US and Japanese market, support for other markets was secondary consideration. It is an inexcapable fact that 480 row plasmas throw away 20% of PAL picture information when they downscale vertical resolution.

StooMonster

A PAL picture scans top to bottom line by line at 50Hz with vacant lines separating each line.
Most of the time most of the area of the screen is in fact black, you don't see this because you eyes integrate (average)the light over a complete frame period.
The interlaced lines effectively get blurred together by the averaging of yor perception so you no longer see destinctive line separation (if you did or could the flicker would drive you crazy).

[StooMonster]

Originally Posted by MAT365

A PAL picture scans top to bottom line by line at 50Hz with vacant lines separating each line.
Most of the time most of the area of the screen is in fact black, you don't see this because you eyes integrate (average)the light over a complete frame period.
The interlaced lines effectively get blurred together by the averaging of yor perception so you no longer see destinctive line separation (if you did or could the flicker would drive you crazy).

That is how an interlaced CRT works, that is not how a digital display works.

This is the plasma formum, and we are discussing 480 line plasmas.

StooMonster