What is Upper Field & Lower Field? at DVinfo.net

Matthew Amirkhani · September 19th, 2007, 07:07 PM

Hi guys,

I would lke to learn the difference between upper field & lower field please.

I am sure that there are a lot of people like myself who have no idea as what they are the purpose for it. Which one you choose and when (i.e) for SD & HDV and ....

Thanks in advance
Matthew

Emre Safak · September 19th, 2007, 07:57 PM

http://en.wikipedia.org/wiki/Field_(video)

A field is half of a frame, formed by taking every other line horizontally. The upper field is the half that starts comprises the odd lines, starting from the first. The lower field is the half that comprises the even lines, starting from the second.

Edward Carlson · September 19th, 2007, 07:58 PM

Upper and lower refer to interlaced video. On NTSC TVs, each frame is drawn 60 times a second on the screen. The photon guns draw every other line (upper, or odd) then go back and do the others (lower or even.) It does this because our power cycles at 60 Hz. If you want to take a still from a video with a lot of motion, you need to deinterlace it. Otherwise you will see jaggy lines where there was a lot of motion. These lines are the two fields. If you are playing your video on a regular SD TV, you don't have to do anything. If you are playing back primarily on a computer, you might want to deinterlace to avoid these jaggy lines.

Bill Westbury · September 20th, 2007, 08:49 AM

Edward, that is a great explanation on the subject and I now understand it better. Thanks.

September 19th, 2007, 07:07 PM	#1
Matthew Amirkhani Major Player Join Date: Jan 2007 Location: Toronto, Canada Posts: 279	What is Upper Field & Lower Field? Hi guys, I would lke to learn the difference between upper field & lower field please. I am sure that there are a lot of people like myself who have no idea as what they are the purpose for it. Which one you choose and when (i.e) for SD & HDV and .... Thanks in advance Matthew __________________ Canon XHA1, Brevis 35mm, Manfrotto 028,501,Vegas Pro 10e

September 19th, 2007, 07:57 PM	#2
Emre Safak Trustee Join Date: Feb 2004 Location: Brookline, MA Posts: 1,447	http://en.wikipedia.org/wiki/Field_(video) A field is half of a frame, formed by taking every other line horizontally. The upper field is the half that starts comprises the odd lines, starting from the first. The lower field is the half that comprises the even lines, starting from the second.

September 19th, 2007, 07:58 PM	#3
Edward Carlson Major Player Join Date: Mar 2007 Location: North Hollywood, CA, United States Posts: 807	Upper and lower refer to interlaced video. On NTSC TVs, each frame is drawn 60 times a second on the screen. The photon guns draw every other line (upper, or odd) then go back and do the others (lower or even.) It does this because our power cycles at 60 Hz. If you want to take a still from a video with a lot of motion, you need to deinterlace it. Otherwise you will see jaggy lines where there was a lot of motion. These lines are the two fields. If you are playing your video on a regular SD TV, you don't have to do anything. If you are playing back primarily on a computer, you might want to deinterlace to avoid these jaggy lines.

September 20th, 2007, 08:49 AM	#4
Bill Westbury New Boot Join Date: Feb 2007 Location: Florida Posts: 19	Edward, that is a great explanation on the subject and I now understand it better. Thanks.