Techy progressive scan question

PBE wrote on 4/9/2003, 12:02 AM

I've been wanting to buy one of the newer progressive scan cameras. However before I invest the money, I'd like to clear up a question I have had about them:

I have read that while shooting in progressive scan mode, there is a noticable amount more noise in the video. The reason I read was something like this: 'the signal is droped by 2, but the noise is only droped my the square root of 2'

That make sense to anyone? If so, would you be willing to explain?

Comments

Bill Ravens wrote on 4/9/2003, 8:37 AM

Well, if I reasoned this out...the field rate is cut in half, from 60i to 24p(30p), thus "the signal is dropped by 2". Then, the noise is still a function of the residual noise in each field capture, which is a function of vertical and horizontal info. To me, this implies a root 2 sort of funtion, since the diagonal is root (1+1)..or really, root(4/3)

SonyDennis wrote on 4/9/2003, 12:43 PM

It has to do with the fact that interlaced cameras draw the value for each pixel from two rows of CCD elements. Therefore, the noise gets averaged out. A progressive CCD is essentially a one-to-one mapping from CCD to pixels, so you don't get the averaging. That said, there are many other intracacies (such as the fact that a single CCD element only captures a single color, not full RGB). Also, CCD technology has improved to where this might not be that big of an issue anymore. Get your hands on some well shot footage and compare for yourself.
///d@