Why am I getting lines/pixilations in my scene? 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 August 18th, 2002, 02:28 AM   #1
mjhamson
 
Posts: n/a
Why am I getting lines/pixilations in my scene?

Sorry if this is a really newbie question, but I donít understand this.

I shot a scene that I thought would turn out okay, but whenever the subjects move, I get jagged lines (or pixilation). If you go to http://www.hamson.com/images/pix-hand.jpg you will see what I mean. (Look at the woman's hand in the background)

You will also see that even in static (non-moving) areas, these jagged lines are found as well (the girls shirt for example).

Am I doing something wrong here?
  Reply With Quote
Old August 18th, 2002, 04:51 AM   #2
Major Player
 
Join Date: Oct 2001
Location: Johannesburg, South Africa
Posts: 220
Hi,

at last someone with the same problem....not that it helps but one feels kinda warm to know you're not the only one.

I have been unable to adequately describe my problem, which by the way is the same as yours but manifests itself much worse than yours does as I can also get severe ghosting.

I tried a new video card, went from Voodoo 3 3000 to a MM G550. Went from Prem 5.1c to Prem 6.0. From 256Ram to 512Ram. Formatted the hard drive reinstalled all software. Problem stays.

This is what "Premiere Cow" had to say. "PC monitors do not display interlaced video properly. TV's will not display frame based video with motion properly. You final target will determine which way to go." The problem is that I don't recall having this problem in the early days.

I then deinterlaced the footage and most the problem dissappeared. I have never had to do this before. Do you went you stop the clip in the timeline and then click on it notice that the pixelation dissappears?

Can I send you a 1,2Meg .bmp image to put on your site to really illustrate the problem?

Cheers
Andrew
__________________
PAL XL-1, DV Raptor, Premiere

TOTAL AMATEUR - DOING IT FOR THE FUN
Andrew Leigh is offline   Reply With Quote
Old August 18th, 2002, 07:10 AM   #3
Warden
 
Join Date: Mar 2002
Location: Clearwater, FL
Posts: 8,267
Hi Michael,

Can you give me a little more info about how the images where shot (what mode, what camera, shutter speed etc.) ? Can you also give some information about how you are viewing the images (NTSC monitor, computer screen, etc.)? Is this the first time the lines have appeared or have there been other instances? What I notice quickly is the subjects that display the motion artifacts are in fact not stationary. The boat is moving. The background is not. The lines appear only on the moving subjects. I know the boat wasn't rocking but I feel the lines are probably related to the motion of the boat.

Jeff
Jeff Donald is offline   Reply With Quote
Old August 18th, 2002, 12:08 PM   #4
Regular Crew
 
Join Date: Nov 2001
Location: Denver, CO
Posts: 290
The lines are interlacing artifacts that appear on moving objects. That's just the way NTSC video works. Every other line is from a different moment in time (1/60th of a second to be exact). You can import the picture into a graphics editing program like Photoshop and run a "de-interlacing" filter on it and that will make the lines go away, but will reduce the detail by half (not too noticable to most people with good de-interlacing, but I can always tell 100% of the time when any footage has been de-interlaced). If you use a Canon GL1/2 or XL1/s you can shoot in Frame mode or Slow 30 and you will not have this problem with your captured frames.
Joe Redifer is offline   Reply With Quote
Old August 18th, 2002, 12:34 PM   #5
Major Player
 
Join Date: Oct 2001
Location: Johannesburg, South Africa
Posts: 220
Hi Joe,

I assume the same applies for PAL. I have had my XL-1 for 3 years now, there has always been a slight hint of "pixellating" as displayed on the PC monitor. Now some of my footage has half the entire body ghosted with the lines as shown in Michaels pic. I have just played the raw footage back on a TV and no problems.

I recently did a small project for someone (since deleted) and the ghosting / pixellation transfered in the export. Played back on three other systems the problem is there. If it only appeared on the PC monitor then it would be an irritation but not a problem.

What has changed, your thoughts?

Cheers
Andrew
__________________
PAL XL-1, DV Raptor, Premiere

TOTAL AMATEUR - DOING IT FOR THE FUN
Andrew Leigh is offline   Reply With Quote
Old August 18th, 2002, 11:48 PM   #6
Regular Crew
 
Join Date: Nov 2001
Location: Denver, CO
Posts: 290
Yes, this will happen on PAL as well. If you are making the video for television and you don't plan on using still frame grabs from it, then I wouldn't worry about the lines (motion artifacts) that appear on your computer monitor. Remember, your computer monitor is progressive scan, so the interlacing will always show up like that. No big deal if you just plan to edit and then export back to tape. If it is jittery when transferred back to tape, then the fields got reversed. I'm not sure but I think DV uses the "odd" field first, and it is easy to get them backwards with certain computer editing programs.

Someday when you are bored, try taking your XL1 and panning across a scene while videotaping. Pause the camera and change it to "Frame Mode". Resume recording and then pan across the same scene again. Capture the entire segment (both pans) into your computer. The second pan will look jerkier, but notice how you don't see the lines on the second pan. Perfect for capturing still frames.
Joe Redifer is offline   Reply With Quote
Old August 19th, 2002, 11:19 AM   #7
RED Code Chef
 
Join Date: Oct 2001
Location: Holland
Posts: 12,514
There are a couple of solutions if you are bothered by this (you
do not need to be if your output is TV only!!!!!)

- shoot frame mode/progressive
- de-interlace on your PC during post
__________________

Rob Lohman, visuar@iname.com
DV Info Wrangler & RED Code Chef

Join the DV Challenge | Lady X

Search DVinfo.net for quick answers | Buy from the best: DVinfo.net sponsors
Rob Lohman is offline   Reply With Quote
Old August 19th, 2002, 03:06 PM   #8
mjhamson
 
Posts: n/a
Thanks for the input

I tried searching for my settings, but after reading everyone's input and mucking with the video, I concluded that you guys really do know what you are talking about ( :-) )

All kidding aside, I just wanted to thank everyone for their help.

-michael
  Reply With Quote
Old August 21st, 2002, 07:39 AM   #9
Major Player
 
Join Date: Oct 2001
Location: Johannesburg, South Africa
Posts: 220
Hi Michael,

go read this.

http://www.hut.fi/Misc/Electronics/c...mputer_tv.html

Cheers
Andrew
__________________
PAL XL-1, DV Raptor, Premiere

TOTAL AMATEUR - DOING IT FOR THE FUN
Andrew Leigh 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 05:48 PM.


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