Why am I getting lines/pixilations in my scene? at DVinfo.net

August 18th, 2002, 01:28 AM

Sorry if this is a really newbie question, but I don’t 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?

Andrew Leigh · August 18th, 2002, 03:51 AM

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

Jeff Donald · August 18th, 2002, 06:10 AM

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

Joe Redifer · August 18th, 2002, 11:08 AM

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.

Andrew Leigh · August 18th, 2002, 11:34 AM

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

Joe Redifer · August 18th, 2002, 10:48 PM

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.

Rob Lohman · August 19th, 2002, 10:19 AM

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

August 19th, 2002, 02:06 PM

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

Andrew Leigh · August 21st, 2002, 06:39 AM

Hi Michael,

go read this.

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

Cheers
Andrew

August 18th, 2002, 01:28 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 don’t 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?

August 18th, 2002, 03:51 AM	#2
Andrew Leigh 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

August 18th, 2002, 11:34 AM	#5
Andrew Leigh 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

August 19th, 2002, 10:19 AM	#7
Rob Lohman 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

August 19th, 2002, 02:06 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

August 18th, 2002, 06:10 AM	#3
Jeff Donald Warden Join Date: Mar 2002 Location: Clearwater, FL Posts: 8,287	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

August 18th, 2002, 11:08 AM	#4
Joe Redifer 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.

August 18th, 2002, 10:48 PM	#6
Joe Redifer 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.

August 21st, 2002, 06:39 AM	#9
Andrew Leigh 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