Digital Blockingness Artifact Problem at DVinfo.net

Joseph Andolina · May 14th, 2006, 04:30 AM

I was just reviewing some low light footage shot in 24pn with my XL2. I'm noticing in the darker lower lit areas of the picture on playback a lot of atifiacting going, such as digital artifacting of what I can only discribe as blocking. I notice it more on certain TV's more than others, but it's there none the less. And yet, sometimes on other things I've shot with the XL2 that had totally dark shadows I never noticed that problem. I'm beginning to realize even more the shortcommings of mini-dv. But I'm wondering is there certain settings in camera that I could have used to try and prevent a artifacting problem in low lit areas? Any advice would be appreciated.

Joe

Greg Boston · May 14th, 2006, 08:05 AM

Joseph,

The XL2 is customizable in a way to give you maximum dynamic range so that you can achieve the desired final look in post, or in camera if you like.

That said, the first thing you can do for that is to set Knee to low, and Black to stretch. This will help give you the characteristic gamma 's-curve'. Your hightlights will roll off more gradually as will your blacks. In fact, stretching the blacks will kind of give milky blacks in camera. But that's a good thing cause now you have that low light detail captured and you can manipulate it in post.

I'm still a little concerned about the blockiness though. Might want to run a head cleaner through it just for good measure. If you continue to have issues, a trip to Canon service may be necessary.

-gb-

Joseph Andolina · May 14th, 2006, 09:20 AM

thanks for your response Greg. I'll check what presets I had. But I believe I had the settings you suggested. The blockingness isn't through the entire video. Just in sections of some of the darker areas. If the heads were dirty, I wouldn;t it be a problem through the entire video?

Andrew Khalil · May 14th, 2006, 11:35 AM

If the heads are dirty, it won't be blocky through the whole video, but only at certain points for a couple of seconds.

However, the fact that you mention it only occurs in dark areas of the frame leads me to believe that dirty heads are NOT your problem (blockiness from dirty heads will occur anywhere, not just in dark areas). From what you say, it sounds like it's just sensor noise (grain).

If you could mention which mode/settings you were shooting in it would help and if possible, a frame grab would be great.

Hope this helps

Joseph Andolina · May 14th, 2006, 01:09 PM

Andrew, I was shooting in 24pn, 1/48 shutter. -0- gain. I don't remember all the presets, I'll have to look at that again when I get home tonight. I believe I had the black streched because the blacks do have that milky look to it, not black black quality. I'll try and look into putting up screen grabs for a few shots as soon as possible. One thing I remember noticing, if there is some detail dimly lit in the shot, that's where I see it generally, because in one scene I had the camera pan up into the night sky, and I don;t believe I noticed any artifacting going on, but I'll have to review it again. And I never see the problem in general in well lit shots with other projects. And perhaps the shots could have been more lit. Unfortunetly the Director wanted low lighting, some light off the side of the Actor's face, and real dim ligthing other parts of the frame. But I've seen the XL2 hold up better in past stuff under almost the same ligthing conditions.

May 14th, 2006, 04:30 AM	#1
Joseph Andolina Regular Crew Join Date: Mar 2004 Location: Everett, WA Posts: 178	Digital Blockingness Artifact Problem I was just reviewing some low light footage shot in 24pn with my XL2. I'm noticing in the darker lower lit areas of the picture on playback a lot of atifiacting going, such as digital artifacting of what I can only discribe as blocking. I notice it more on certain TV's more than others, but it's there none the less. And yet, sometimes on other things I've shot with the XL2 that had totally dark shadows I never noticed that problem. I'm beginning to realize even more the shortcommings of mini-dv. But I'm wondering is there certain settings in camera that I could have used to try and prevent a artifacting problem in low lit areas? Any advice would be appreciated. Joe

May 14th, 2006, 08:05 AM	#2
Greg Boston Wrangler Join Date: Oct 2003 Location: DFW area, TX Posts: 6,117 Images: 1	Joseph, The XL2 is customizable in a way to give you maximum dynamic range so that you can achieve the desired final look in post, or in camera if you like. That said, the first thing you can do for that is to set Knee to low, and Black to stretch. This will help give you the characteristic gamma 's-curve'. Your hightlights will roll off more gradually as will your blacks. In fact, stretching the blacks will kind of give milky blacks in camera. But that's a good thing cause now you have that low light detail captured and you can manipulate it in post. I'm still a little concerned about the blockiness though. Might want to run a head cleaner through it just for good measure. If you continue to have issues, a trip to Canon service may be necessary. -gb-

May 14th, 2006, 09:20 AM	#3
Joseph Andolina Regular Crew Join Date: Mar 2004 Location: Everett, WA Posts: 178	thanks for your response Greg. I'll check what presets I had. But I believe I had the settings you suggested. The blockingness isn't through the entire video. Just in sections of some of the darker areas. If the heads were dirty, I wouldn;t it be a problem through the entire video?

May 14th, 2006, 11:35 AM	#4
Andrew Khalil Major Player Join Date: Jun 2005 Posts: 424	If the heads are dirty, it won't be blocky through the whole video, but only at certain points for a couple of seconds. However, the fact that you mention it only occurs in dark areas of the frame leads me to believe that dirty heads are NOT your problem (blockiness from dirty heads will occur anywhere, not just in dark areas). From what you say, it sounds like it's just sensor noise (grain). If you could mention which mode/settings you were shooting in it would help and if possible, a frame grab would be great. Hope this helps

May 14th, 2006, 01:09 PM	#5
Joseph Andolina Regular Crew Join Date: Mar 2004 Location: Everett, WA Posts: 178	Andrew, I was shooting in 24pn, 1/48 shutter. -0- gain. I don't remember all the presets, I'll have to look at that again when I get home tonight. I believe I had the black streched because the blacks do have that milky look to it, not black black quality. I'll try and look into putting up screen grabs for a few shots as soon as possible. One thing I remember noticing, if there is some detail dimly lit in the shot, that's where I see it generally, because in one scene I had the camera pan up into the night sky, and I don;t believe I noticed any artifacting going on, but I'll have to review it again. And I never see the problem in general in well lit shots with other projects. And perhaps the shots could have been more lit. Unfortunetly the Director wanted low lighting, some light off the side of the Actor's face, and real dim ligthing other parts of the frame. But I've seen the XL2 hold up better in past stuff under almost the same ligthing conditions.