Artifacting in Video
 

Hello,

I've been shooting some with my new XL2 and I've noticed some strange stairstepping or mosaic patterns in the same areas of the video. I've uploaded a recent commercial spot I've created, and I am greatly concerned with this. Can anyone identify what the problem might be and whether service is in order. Thanks!!

http://rapidshare.com/files/35301824..._test.wmv.html

RP

Looks to me like a perfect example of interlaced video on a computer monitor.

If this is for viewing on television, it will take care of itself.

If this is for viewing on the Web, you need to convert from interlaced to progressive.

This video was rendered as a high quality .wmv. Isn't that format non-interlaced? I have also rendered this from the timeline as a progressive scan mpeg-2 with the same result. Is there something I'm missing?
Thanks!

RP

No one else has any suggestions? My previous DV camcorders never exhibited this issue. Can it be a service issue? Is there a possibility that there's a pc problem or my NLE...anyone..please????/

RP

Hi Rick,
To me it looks like oversaturated reds. I saw (and experiment) that issue many times with very strong reds (and specially with canon cameras). Possible solutions:
1. avoid strong reds
2. turn down a bit the saturation when shooting
3. turn a bit down the red gain

You can make a simple test. Pick a very red object and try some seconds with the normal saturation and with the saturation down and even with an oversaturation and look at the footage. It will take only some minutes to do it. I bet that 99,9% thats the problem.
On how to solve the already shooted footage is more complex but is also possible (not to 100% but to make look better)

Martin,

Thanks for the reply. I am going to do some testing shortly and see if the factory default setting exhibits the same issue. FYI, I used the "Technicolor" preset found here in the DVI Forums; I wonder, has anyone else had this issue arise when using this preset?

For the interim, I have contacted Canon service and if the factory default test yields the same results as the "Technicolor" preset, I'll drop it off at the Jamesburg facility.

Any additional wisdom is greatly apreciated!

Thanks to all

RP

Rick,

Martin is right on with the reds. This was my first problem with this camera. The first thing I ever shot with it was a sailboat race that happened to have one boat with a bright red sail. I also used the Technicolor preset since there were some nice vibrant colors on the lake that day. It freaked me out too since the camera I had before my XL-2 never showed much of this. After alot of research on this site and others I've found thats just the way 4:1:1 DV handles reds. I also borrowed my friends XL-2 and did a side by side test and they were identical with red artifacts. The scopes matched perfectly in FCP for both cameras.

If I have control over my set or location now I try to avoid the color completely. If you have no choice or have already shot some footage you have to use, you can use a chroma blur filter like the one available in the Nattress set in conjunction with a 3 way color corrector that most NLE's have. It took me alot of experimenting to get around this but it is possible.

Mike,

Thanks for the confirmation; you and Martin have likely saved me a trip to Canon service. I must admit though, what a heinous design flaw. I mean I shoot commercials like the example "run-and-gun" style all the time and I just don't have the time or freedom to simply avoid one of only 3 spectral colors which the camera sees. I never had experienced this type of limitation with a DV cam before - maybe I should try and dump this XL2 and get another SD sub 5K cam? I don't mean to gripe, but suggesting avoiding reds with a new video camera is like suggesting avoiding turns with a new car...isn't it?

Thanks again,

RP

Hi Rick. Rather than avoiding reds, can't you just turn down the red gain a bit? Or reduce the overall colour gain if you don't want to change the balance? Just a suggestion.

Richard

Richard,

Of course I can reduce the saturation, but from what Mike stated, this is an inherent problem with this cam and as he suggested "avoid reds completely."
I'm going to try shooting with the factory default in the field and adjust saturation in post - hopefully this artifacting issue can be contained, although I'm really disappointed that I cannot acquire the vivid "poppy" shots I was looking for my digital signage commercials. I still may consider a different camera. I'm pretty bummed out at the moment I must admit.

RP

Hi Rick. I just looked at an old thread where Barry Goyette introduced his technicolor preset. Extract below. So basically it looks like you are setting the saturation too high for the conditions.

Of course you should never have to avoid reds completely, maybe just avoid presets that boost reds when it is not appropriate. I very much doubt that is a camera problem. Try some different settings, that is one of the great strengths of this cam, that you can adjust so many things to get the results you want in different conditions.

Richard

":Barry's SuperPolarized Technicolor Dream

Gamma: Cine
Knee & Black: Middle
Color Matrix: Cine
Color Gain: +4
Color Phase: neutral
R gain: +2
G gain: +3
B Gain: -2

Realistically your white balance will effect how you position the R,G,B Gains...Mine was designed to pump the yellow-red portion of the spectrum. Also, for anyone with sane mind...this setting is really too saturated...so I would play with adjusting the Color Gain down to +1 or +2 for a saturated, but more natural display of color. I'll try to post some images later."

Rick,

I didn't mean to say that you should avoid reds completely. There are ways of dealing with it before it gets on to tape as many have mentioned. I should have been more specific and said that I avoid bright highly saturated reds if I can. I shoot them all the time and the muted reds or variations of pink and purple are fine.

Dropping the color saturation and the red gain does make a significant difference. Do some experiments at home with a decent monitor and adjust your settings accordingly to what you see. You will learn how to take the curve off of those blocky images and what to do in those situations when your shooting without a monitor. This is a fantastic camera and I have seen this issue in many different cameras. Its not specific to Canon cameras by any means but from what I understand more of a color compression issue inherent to the format.

Hey Guys,

Thanks for taking the time to clarify this issue further. I am not an indy film maker, nor am I doing lengthy productions of any sort at this time. I produce brief spots for display on my rapidly growing out-of-home video/dynamic ad network (digital signage).

I include video production with my ad rates to entice large numbers of advertisers and I respectively permit 90 minutes of shooting time per client which includes setting up a couple of pre-assembled tungsten lights, finishing my coffee, and packing it up.

Hence, I simply don't have the luxury of time to get overly technical with this camera on any single location. Moreover, at this time a field monitor is not practical both in terms of time constraints and expense. Currently, all I have is an LCD and the camera’s settings do not really show up on it.

To simplify things for my purposes - again namely run and gun stuff in unlimited circumstances, seeking vivid, eye-catching pop with minimal danger of inducing the artifacting - is there a good general purpose preset to use with this camera to achieve this without blowing the proverbial curve?

Also, I am experiencing some other anomalies which I’ll get into another day with this XL2. For now, I’d like to simplify the preset issue to preclude problems on the next shoot.

Thanks again!

RP

Hi Rick. To be honest, you need to be prepared to tweak this cam according to the shot conditions. But if you are able to invest some time (in advance of the next gig) into seeing what works best in different types of lighting, you can prepare a couple (maybe 3) of settings that will give you great results most of the time. What Mike Andrade says about using a monitor at home is spot on. Only by using a larger monitor will you really see the difference that the various settings are making. And only by playing around with these settings will you get a feel for what to adjust when you are out on a shoot.

If you don't want to do this (not a criticism - many people prefer not to have to adjust the camera all the time) then maybe you could look at a different camera such as a Sony PD170. It has better low light performance than the XL2, and will rarely produce a bad shot. The image is not as good as a well setup XL2, but it take less hassle to get it. (I'll probably get flak for posting this here, but it's what I believe).

But since you already have the XL2, I would advise that you try and work out how to get the results you need from it.

If it doesn't work out after a reasonable amount of time and effort, then you could think more seriously about replacing it.

Richard

Hi Rick,
You dont need lots of time to avoid this problem (well, may be only in very special cases).
I´v made many filmings with strong reds and simply with turning down one or two notches the saturation or the red gain you can avoid the problem (that is not inherent to canon cameras even if canons are more sensitive to that issue, I saw this problem even with very expensive cameras from every brand).
That can take to you something around 10 to 20 seconds.
If you like exploding reds then you can turn up in post.
You dont have to avoid reds.

Rick, I agree with the hot red issue with the XL2, but this is not the problem with the clip.

This advert clip is showing the effects of interlaced captured clips 60/50i. The source clips need to be de-interlaced first or shoot in the 24/25p mode.

If you the 60/50i source clip at 100% resolution on your LCD computer screen you will see interlaced lines.

This is not an issue with the XL2, it's due to the 4:1:1 chroma subsampling used by the DV format. Blocky reds can be more visible on the XL2 if you're using certain camera settings, because doing so pushes the camera beyond what the recording format it uses can handle. Don't fault Canon if you must find fault--fault the engineers who designed the DV standard in the 1990's, if anyone. In their defense, DV was designed to be a consumer format, and no one really had any idea at the time that professionals would end up using it. What this means is that there are certain nasty things that we have to work around unless we want to shell out for cameras that use a more capable format. The way in which DV handles reds and oranges is one of those nasty things.

The partial solution to the issue, as others have noted, is to turn down the color gain and/or red gain in shooting situations where you're likely to encounter this problem. As one poster suggested, a better solution is to simply use some chroma blur in post, but this will only work if you're rendering directly from your timeline into some format other than DV--one that doesn't subsample chroma information in 4:1:1 (like WMV, DVD MPEG-2, etc.). If you apply chroma blur and render back to DV again, the "blockies" will simply reappear just like before.

Also note that the problem we're discussing here will show up differently on a TV than it will on a computer monitor: on the TV, you'll see a "blooming" "aura" of red around the affected area, while on a monitor, you'll get the blockiness we've been talking about.

Jarrod - I didn't see James' remark as being critical of Canon, or finding fault with anyone. The OP shot the offending footage on an XL2, and I saw James' comments to be a simple reference to that.

He said that reds were an "issue with the XL2." I was simply pointing out that that reds are an issue with the DV standard.

Hey fellas,

Thanks again for the assist. I must say however, I've never experienced this issue with the Sony PD-150/250 – as suggested isolating this issue to the DV standard.

I still find it ponderous that the XL2 artifacting occurs so prominently in areas where red is not in high saturations to begin with (I’ll upload another example of this issue in strong blue areas). I hope to do some tests over this weekend and see if I can simply shoot in factory default and tweak the footage in post – obviating the need to adjust those settings every time I change lighting situations.

I wonder for the sake of attempting to create a “run and gun” setting or two for myself, can I use a consumer LCD TV? My funds are currently allocated for deployment of my signage network right now – a 2K field monitor is not within my reach at the moment.

My shooting situations as I’ve previously mentioned are dramatically inconsistent to a fault; in and out of business locations – tungsten to God’s own grid-lighting system. It’s tough enough to meet the client, set up, unpack, think about the shots (I believe in pre-editing the piece in my mind before the shot), set exposure, depth of field, etc. etc. to be hassled with tweaking those darned settings – just not practical in my case.

I’d really love for the XL2 to suit my shooting needs by virtue of using the default settings and tweaking in post or by finding a decent median preset whereby I can “run and gun” and still acquire good quality, multipurpose footage. After all, I just blew over 4K on this puppy with the case and batteries, etc. And yes, I realize some broadcast lenses cost in excess of 4K, but I’m not shooting for Discovery’s Planet Earth here!

I do wonder however, other than the PD-170, which quite frankly is too small for me – I need a shoulder cam; is there a decent sub 5K or mid 5K cam which requires less setting romancing with respect to my shooting requirements, i.e. JVC DV5100U?

Here’s another recent example of the artifacting – notice the stair-stepping on the gent’s blue sleeve cuffs:

http://rapidshare.com/files/36209112/wilson2.wmv.html

Thanks again,

RP

As I was saying before, the issue is more visible on an XL2 sometimes because of the amount of control you have over the way color is reproduced. If you adjust an XL2 so that the image resembles what you'd get from one of the Sonys, I'll betcha the reds in each of the images end up looking pretty similar.

Blocky colors are a compression issue (they are a result of 4:1:1 chroma sampling--color pixels are bigger than light pixels, to phrase it in layman's terms). Sony DV cameras and Canon DV cameras use the same compression scheme--DV. Follow the syllogism to its logical conclusion. :)

Well, let's see down which path this syllogism takes us. ;-)

I'm still open to suggestions regarding replacement or median / multi-purpose setting(s). I still see other issues with this camera which I'll reveal shortly - not as a critisism, but in search of solution(s).

For the short term I've gotta make due with this camera and get it to work - I done hocked my Sony Gear.

RP