how do i prevent this? at DVinfo.net

Go Back   DV Info Net > The Tools of DV and HD Production > Open DV Discussion

Open DV Discussion
For topics which don't fit into any of the other categories.


Reply
 
Thread Tools Search this Thread
Old April 10th, 2008, 02:22 PM   #1
Regular Crew
 
Join Date: Nov 2007
Location: UK
Posts: 57
how do i prevent this?

i keep having problems with this ghosting on moving images, is there a way to prevent it?

http://i58.photobucket.com/albums/g2...sid/Image1.jpg

hope someone can help

thanks
Kev O'Brien is offline   Reply With Quote
Old April 10th, 2008, 02:45 PM   #2
Regular Crew
 
Join Date: Sep 2005
Posts: 35
Increase the shutter speed maybe....
Charlie Gillespie is offline   Reply With Quote
Old April 10th, 2008, 03:12 PM   #3
Inner Circle
 
Join Date: Jan 2006
Location: Minnesota (USA)
Posts: 2,171
What camera are you shooting with Kev?
Robert M Wright is offline   Reply With Quote
Old April 10th, 2008, 03:17 PM   #4
Regular Crew
 
Join Date: Nov 2007
Location: UK
Posts: 57
Quote:
Originally Posted by Robert M Wright View Post
What camera are you shooting with Kev?
its a canon xh-a1 shot at 50i im shooting a high shutter speeds already 250-500 and its fine for most of the footage but for some of the kitesurfing tricks im using extreme slo mo which then shows it up
Kev O'Brien is offline   Reply With Quote
Old April 10th, 2008, 03:20 PM   #5
Inner Circle
 
Join Date: Jan 2006
Location: Minnesota (USA)
Posts: 2,171
That's interlace artifacts. On a progressive display, you are seeing 2 fields (at the same time) shot 1/50th of a second apart. You can deinterlace the footage or shoot 25F to get rid of that on a progressive display.
Robert M Wright is offline   Reply With Quote
Old April 10th, 2008, 03:28 PM   #6
Major Player
 
Join Date: Oct 2003
Location: Salt Lake City, UT
Posts: 256
You don't mention what editing program you are using, but if it is showing up just with slow motion footage I would guess that the ghosting in caused by frame blending. Since the A1 can't overcrank, when you slow it down it has to take the existing frames and do some form of duplication. For example, if you slow it down to 50% the software could just duplicate each frame so it is showing twice instead of once. When you view this at normal speed the footage looks slowed down. Since this simple form of slow motion can look jerky many programs will 'blend' frames, meaning rather than simply duplicating the previous frame they create a new frame by blending the previous frame with the next frame. Depending on how well the software does this you can get ghosting like is shown in your example.

The problem can also be caused by the software creating a progressive image from an interlaced one. Although you can see it in the frame you posted, when you view the video at normal viewing speed you may not notice it.
Lloyd Coleman is offline   Reply With Quote
Old April 10th, 2008, 03:36 PM   #7
Inner Circle
 
Join Date: Jan 2006
Location: Minnesota (USA)
Posts: 2,171
Take a frame grab from a 1080 line interlaced video (2 fields 1/50th of a second apart), of something moving quickly, shot at a high shutter speed, resize the image to 439 lines and a it will look like that every time.
Robert M Wright is offline   Reply With Quote
Old April 10th, 2008, 03:45 PM   #8
Inner Circle
 
Join Date: Jan 2006
Location: Minnesota (USA)
Posts: 2,171
The posted image is deceptive, because resizing has effectively blended the fields (which eliminates the interlace lines you would see in the full size image).
Robert M Wright is offline   Reply With Quote
Old April 10th, 2008, 04:27 PM   #9
Regular Crew
 
Join Date: Nov 2007
Location: UK
Posts: 57
your loosing me a bit :-/

im down converting my footage from the a1 and editing in sony vegas pro 8

on my footage propertys it says that its lower field first so i set my project propertys to that and have it set to interpolate fields

what would you recomend i change?
Kev O'Brien is offline   Reply With Quote
Old April 10th, 2008, 04:36 PM   #10
Inner Circle
 
Join Date: Jan 2006
Location: Minnesota (USA)
Posts: 2,171
Deinterlace the footage before downsizing it.
Robert M Wright is offline   Reply With Quote
Old April 10th, 2008, 04:38 PM   #11
Regular Crew
 
Join Date: Nov 2007
Location: UK
Posts: 57
im downconverting it direct from the camera using the downconvert function

should i render the footage before i edit?
Kev O'Brien is offline   Reply With Quote
Old April 10th, 2008, 05:39 PM   #12
Inner Circle
 
Join Date: Jan 2006
Location: Minnesota (USA)
Posts: 2,171
To get rid of that ghosting effect, you'll need to capture it as HDV, rather than have the camera convert it to DV for capture.
Robert M Wright is offline   Reply With Quote
Old April 10th, 2008, 05:41 PM   #13
Regular Crew
 
Join Date: Nov 2007
Location: UK
Posts: 57
ok thanks i will give it a try and play around a bit

thanks for your time
Kev O'Brien is offline   Reply With Quote
Old April 10th, 2008, 05:49 PM   #14
Inner Circle
 
Join Date: Jan 2006
Location: Minnesota (USA)
Posts: 2,171
I don't know what I was thinking there for a minute. (I'm in rough shape today - having a lot of pain.) You could deinterlace the DV downconverted by the camera for capture, but it would work a lot better to deinterlace the original recorded HDV. A simple method would be to discard a field. You could also deinterlace to 50p, which would be great for slow-mo, but that would get more involved (and take more work).
Robert M Wright is offline   Reply
Reply

DV Info Net refers all where-to-buy and where-to-rent questions exclusively to these trusted full line dealers and rental houses...

Professional Video
(800) 833-4801
Portland, OR

B&H Photo Video
(866) 521-7381
New York, NY

Z.G.C.
(973) 335-4460
Mountain Lakes, NJ

Abel Cine Tech
(888) 700-4416
N.Y. NY & L.A. CA

Precision Camera
(800) 677-1023
Austin, TX

DV Info Net also encourages you to support local businesses and buy from an authorized dealer in your neighborhood.
  You are here: DV Info Net > The Tools of DV and HD Production > Open DV Discussion

Thread Tools Search this Thread
Search this Thread:

Advanced Search

 



Google
 

All times are GMT -6. The time now is 06:47 PM.


DV Info Net -- Real Names, Real People, Real Info!
1998-2017 The Digital Video Information Network