How does a PAL Sony camera get 576 lines?

Mike Rehmus · September 13th, 2005, 09:13 PM

Not quite. NTSC according to the FTC, has to have 525 lines. No more, no less. But you cannot see all of them because some are reserved for vertical retrace (a CRT pheonomena) and other uses.

There is also a lot of confusion between resolution and addressability.

It is easy for our computers to address 720 by 480 points. It is impossible for a normal CRT-based SD television to display that much information in a discrete manner. That is, you cannot get close to the screen and count 720 by 480 points. You will be doing well if you could count half that on a brand new set that is properly adjusted.

Discretly addressed displays . . . LCD, Plasma, etc., can have pixels that can be addressed at that manner but only if you deliver a pure digital signal, something NTSC is not and never will be. So what you get is something close. Usually. Assuming the line-doubler or other signal processors get it right.

Digital television can get it right. Except few of us have one. Digital television is not the same thing as HD by the way.

Tom Hardwick · September 13th, 2005, 11:54 PM

You say you're starting to understand Laurence, but you're still a some way off. NTSC is 480 lines, not 580, and the 4:1:1 colour is no better or worse than PAL's 4:2:0, only different. The DV format itself is limited to a theoretical 530 lines of horizontal resolution, not 500, and yes, standard DVDs use the full 720 x 576 raster, or in your case 720 x 480. But if you show a 16:9 DVD on a 4:3 TV you lose a lot of image detail, as rather than showing 576 (PAL) picture lines, it only displays 430.

tom.

Graeme Nattress · September 14th, 2005, 07:00 AM

But that's 530 lines per picture height, which is very close to 720 lines (regardless of picture height). See my earlier post....

Graeme

Giroud Francois · September 14th, 2005, 07:10 AM

you will drive him nuts....

Tom Hardwick · September 14th, 2005, 07:38 AM

Sorry Graeme? The 432 picture information lines are simply because the other 144 lines are the black bars top and bottom of the picture. 576 minus 25% = 432.

tom.

Graeme Nattress · September 14th, 2005, 08:10 AM

Now I'm getting confused.....

Graeme

Laurence Kingston · September 14th, 2005, 08:47 AM

Quote:

Originally Posted by Tom Hardwick

You say you're starting to understand Laurence, but you're still a some way off. NTSC is 480 lines, not 580, and the 4:1:1 colour is no better or worse than PAL's 4:2:0, only different. The DV format itself is limited to a theoretical 530 lines of horizontal resolution, not 500, and yes, standard DVDs use the full 720 x 576 raster, or in your case 720 x 480. But if you show a 16:9 DVD on a 4:3 TV you lose a lot of image detail, as rather than showing 576 (PAL) picture lines, it only displays 430.

tom.

"580" instead of "480" was a typo. So if the DV format is limited to 530 lines, the Sony cameras are right at the theoretical limit. I suppose I can't ask for more than that ;)

Mike Rehmus · September 14th, 2005, 10:33 AM

Making it even more confusing is the point that what you've been discussing about DV is the recording resolution, not the resolution you could measure if you pointed the camera at a resolution chart.

You'd have to have a very good camera, a very good camera to actually get close to delivering the theoretical maximum resolution when actually pointing it at a real-world target.

I don't think the fixed-lens SD cameras come close. That's why for people who can work in relatively bright shooting environments are picking the HDV cameras but only doing SD work. The optical system is better and the SD image should be better.

September 13th, 2005, 09:13 PM	#16
Mike Rehmus Wrangler Join Date: May 2002 Location: Vallejo, California Posts: 4,049	Not quite. NTSC according to the FTC, has to have 525 lines. No more, no less. But you cannot see all of them because some are reserved for vertical retrace (a CRT pheonomena) and other uses. There is also a lot of confusion between resolution and addressability. It is easy for our computers to address 720 by 480 points. It is impossible for a normal CRT-based SD television to display that much information in a discrete manner. That is, you cannot get close to the screen and count 720 by 480 points. You will be doing well if you could count half that on a brand new set that is properly adjusted. Discretly addressed displays . . . LCD, Plasma, etc., can have pixels that can be addressed at that manner but only if you deliver a pure digital signal, something NTSC is not and never will be. So what you get is something close. Usually. Assuming the line-doubler or other signal processors get it right. Digital television can get it right. Except few of us have one. Digital television is not the same thing as HD by the way. __________________ Mike Rehmus Hey, I can see the carrot at the end of the tunnel!

September 14th, 2005, 07:00 AM	#18
Graeme Nattress RED Problem Solver Join Date: Sep 2003 Location: Ottawa, Canada Posts: 1,365	But that's 530 lines per picture height, which is very close to 720 lines (regardless of picture height). See my earlier post.... Graeme __________________ www.nattress.com - filters for FCP

September 14th, 2005, 08:10 AM	#21
Graeme Nattress RED Problem Solver Join Date: Sep 2003 Location: Ottawa, Canada Posts: 1,365	Now I'm getting confused..... Graeme __________________ www.nattress.com - filters for FCP

September 14th, 2005, 10:33 AM	#23
Mike Rehmus Wrangler Join Date: May 2002 Location: Vallejo, California Posts: 4,049	Making it even more confusing is the point that what you've been discussing about DV is the recording resolution, not the resolution you could measure if you pointed the camera at a resolution chart. You'd have to have a very good camera, a very good camera to actually get close to delivering the theoretical maximum resolution when actually pointing it at a real-world target. I don't think the fixed-lens SD cameras come close. That's why for people who can work in relatively bright shooting environments are picking the HDV cameras but only doing SD work. The optical system is better and the SD image should be better. __________________ Mike Rehmus Hey, I can see the carrot at the end of the tunnel!

September 13th, 2005, 11:54 PM	#17
Tom Hardwick Inner Circle Join Date: Mar 2003 Location: Billericay, England UK Posts: 4,711	You say you're starting to understand Laurence, but you're still a some way off. NTSC is 480 lines, not 580, and the 4:1:1 colour is no better or worse than PAL's 4:2:0, only different. The DV format itself is limited to a theoretical 530 lines of horizontal resolution, not 500, and yes, standard DVDs use the full 720 x 576 raster, or in your case 720 x 480. But if you show a 16:9 DVD on a 4:3 TV you lose a lot of image detail, as rather than showing 576 (PAL) picture lines, it only displays 430. tom.

September 14th, 2005, 07:10 AM	#19
Giroud Francois Inner Circle Join Date: Feb 2004 Location: switzerland Posts: 2,133	you will drive him nuts....

September 14th, 2005, 07:38 AM	#20
Tom Hardwick Inner Circle Join Date: Mar 2003 Location: Billericay, England UK Posts: 4,711	Sorry Graeme? The 432 picture information lines are simply because the other 144 lines are the black bars top and bottom of the picture. 576 minus 25% = 432. tom.