|
|
|
future technology tv Complaints about the BBC's HD service rumble on
|
|
I expect they'll announce Super HD shortly - after all the set makers have to be kept busy - and the whole sorry thing will repeat... They already have Ultra HD. http://news.bbc.co.uk/1/hi/technology/5335870.stm I would hope in the future we would get away from the strange to me at least 16x9 ratio Think this might have been done probably due to limitations of the CRT. I would like to see the cinema screen ratio used in the future. Yes I know the movie screens vary but is the normal w/s 2:1? Going up to 2.5:1 for the epic _style_ films? I hate 2.25/2.35 ratio, at least for films to be shown on TV. My heart sinks everytime I put a DVD on or watch a movie on TV, and it's in letterbox format. Apart from the fact that none of my TV's zoom functions scale equally in X and Y (so distorting the picture), it means at least 100 lines of vertical SDTV resolution is wasted. Worse are the letterbox formats designed to fit into a 4:3 _frame_, which I calculate are only using 320 lines of vertical resolution (I remember trying to watch Grand Prix, originally in 70mm, in this format, on TCM, which does not believe in high bitrates either). Why can't the transmitted picture use the full SDTV height, then be stretched horizontally in the TV? Better still, transmit only the 16:9 central portion, to preserve horizontal resolution too.
|
|
|
|
|
|
|
The administrator has disabled public write access. |
|
|
|
future technology tv Complaints about the BBC's HD service rumble on
|
|
|
Why can't the transmitted picture use the full SDTV height, then be stretched horizontally in the TV? Better still, transmit only the 16:9 central portion, to preserve horizontal resolution too. Isn't that what normally happens? SDTV is transmitted at 720x576pixels and single byte in the MPEG stream tells the TV what aspect ratio to display it at.
|
|
|
|
|
|
|
The administrator has disabled public write access. |
|
|
|
future technology tv Complaints about the BBC's HD service rumble on
|
|
Indicating the resolution as the total number of pixels in the image is a perfectly valid way of doing so, but I doubt that most people would think it the most obvious one to use, as the relatioship between the numbers and perceived sharpness is no longer a simple one, but a square law. It ceased to be a square law for most cameras a long time ago, Rod, and for some cameras it is much less than linear. It certainly isn't a simple relationship between resolution and pixel count. 
|
|
|
|
|
|
|
The administrator has disabled public write access. |
|
|
|
future technology tv Complaints about the BBC's HD service rumble on
|
|
|
The concept of resolution as lines per linear distance has been in use a lot longer than that. What an interesting discussion, and there was I thinking that the term resolution was first used with telescopes, way back in the 18th century, where of course it is measured in arc seconds Exactly. A linear measurement related to the size of detail you can see. If the number of detail elements per unit *area*, rather than *distance*, had ever been thought to be important, we'd have been using something like millisteradians. The concept of indicating the number of detail elements within an area seems to have arisen recently amongst those who are selling them, and who can thereby use bigger and more impressive (if misleading) numbers. Rod.
|
|
|
|
|
|
|
The administrator has disabled public write access. |
|
|
|
future technology tv Complaints about the BBC's HD service rumble on
|
|
|
In article <QA4Ym.17918$
This e-mail address is being protected from spam bots, you need JavaScript enabled to view it
, bartc <
This e-mail address is being protected from spam bots, you need JavaScript enabled to view it
writes Why can't the transmitted picture use the full SDTV height, then be stretched horizontally in the TV? Better still, transmit only the 16:9 central portion, to preserve horizontal resolution too. Isn't that what normally happens? SDTV is transmitted at 720x576pixels and single byte in the MPEG stream tells the TV what aspect ratio to display it at. Everything I've seen suggests the black bars, top and bottom, are transmitted as part of the picture (and some channels I've seen have station logos over these bars). When an entire 2.25:1 movie image is shown, all 720 horizontal pixels are used, many of which will be thrown away if the picture is digitally zoomed by the TV to eliminate the black bars. In this case, on a 16:9 TV, you will be looking at some 560Hx450V pixels' worth of detail, about 60% of what SDTV can deliver. And in the case of my TCM movie example, over HDMI the 4:3 image could not be zoomed by my TV, and the 2.25:1 movie contained in the _frame_ occupied about 55% of the screen area of my 26 TV. The only thing that looks good is material shot in 16:9, 'compressed' to fit into 720x576, and 'expanded' at the TV to perfectly fill the screen with no aspect distortion (the pixels have been stretched horizontally compared with the 4:3 SD was designed for, but the compression and expansion cancel each other). 100% utilisation of both resolution and screen area, and no distortion; why can't all programs be like that?
|
|
|
|
|
|
|
The administrator has disabled public write access. |
|
|
|
future technology tv Complaints about the BBC's HD service rumble on
|
|
|
The concept of resolution as lines per linear distance has been in use a lot longer than that. What an interesting discussion, and there was I thinking that the term resolution was first used with telescopes, way back in the 18th century, where of course it is measured in arc seconds Exactly. A linear measurement related to the size of detail you can see. If the number of detail elements per unit *area*, rather than *distance*, had ever been thought to be important, we'd have been using something like millisteradians. The concept of indicating the number of detail elements within an area seems to have arisen recently amongst those who are selling them, and who can thereby use bigger and more impressive (if misleading) numbers. Except, of course, that an arc second is not a linear measurement at all but an angular measurement, which gives a linear component only at a specified distance. It seems to me that a number expressing the *content* of a picture in terms of the total number of picture elements it contains is a perfectly valid means of indicating the amount of detail contained in a picture. Picture content expressed as the product of the number of lines or pixels in the height and width, as say 1920 x 1080 or 2.07 megapixels, has the advantage of being independent of aspect ratio. Resolution doesn't come into it. How much of the detail can actually be seen of course depends on the size of the display, the viewing distance, and the resolution of the viewers eyesight (which can be measured in arc seconds).
|
|
|
|
|
|
|
The administrator has disabled public write access. |
|
Favoured: 0
42-year-old Anne Quemere marched today from San Fancisco and intends to cross the Pacific. None kitesurfer have not yet done. 
