Digital Video, NTSC, and # of lines

[ProfessorU]

As I understand it, the standard for digital TV-video editing is

720x480 at .9 pixel aspect ratio for 4:3, 1.2 pixel aspect ratio for 16:9, or 640x480 on a computer screen. In all cases, 480 lines of resolution.

So why does everything I read about NTSC, and about MiniDV, mention either 520, 525, 530 or 'more than 500' lines of resolution?

For example:
http://www.canondv.com/gl2/f_dv_format.html
http://www.its.bldrdoc.gov/fs-1037/dir-025/_3611.htm
http://www.powerdv.com/cgi-global/ge...i?p=dv-gvd1000 (see the specifications at the bottom)

I'm using a Canon GL2 and Premiere 6.5. Premiere won't sucessfully capture video at anything other than 480 lines.

Maybe I should send an email to canon but I'm hoping one of the gurus here knows what's up.

[Platypus]

The resolution you're referring to is horizontal resolution, but this isn't about horizontal lines. It can be confusing initially, but the horizontal scan lines set the vertical resolution, and vice versa.

Think of it this way: the horizontal lines in the image are "stacked" vertically to create the image, and how many there are control how much detail can be resolved up and down the image (the vertical resolution). When the image is scanned with a raster on a TV screen, these are actually lines as a beam is swept across the screen from top to bottom.

The horizontal resolution is also described as so many "lines", and defines how much detail can be resolved sideways across the image (the horizontal resolution. On a CRT TV screen image, this is limited by the performance of the circuitry in the TV and the VCR or whatever the image is coming from. There aren't really "lines" setting the resolution, but it's described in the same terms to show how much horizontal resolution there would be if it really was governed by lines stacked sideways in the same way.

A VHS for example can resolve horizontal detail as if there were about 250 or so lines "stacked" across the screen, S-VHS is better.

DV captures data at the resolutions you have mentioned. So consider that there are at least 640 "lines" that can be thought of as being "stacked" across the screen to form the image. Allowing for some issues like overscan that occurs in video images, the horizontal resolution ends up being able to resolve horizontal detail as if there were 500-odd lines, ie about twice the resolution of a standard analog VHS recorder.