View Full Version : DVX-100A and bright red objects
Bruce A. Christenson July 3rd, 2005, 05:57 PM I shot some footage yesterday, and one of my guys was wearing a bright red baseball cap. In almost all of the screencaps I collected today, there is major blurring/compression on the red edges. Is this normal? Is there anything I can do in post or in the future during shooting to prevent this? Avoid St. Louis fans?
I'm using a DVX-100A, Vegas 5.0, screencaps right from the timeline ("best, full").
Examples:
http://www.piousdogproductions.com/jpg/Image6.jpg
http://www.piousdogproductions.com/jpg/Image10.jpg
http://www.piousdogproductions.com/jpg/Image12.jpg
Image indexes go from 0 to 23, in case anyone wants to check out the rest of the screencaps from my shoot.
Thanks,
[bac]
Daniel Runyon July 3rd, 2005, 09:44 PM Yessir....Scharky at DVXuser.com discovered that a bit of chroma blur in post does wonders for this.
Ash Greyson July 3rd, 2005, 11:30 PM One of the prices you pay for the saturated colors the DVX delivers. XL2 handles these situations much better, but of course, less saturation in general. Both are correctable in post but I generally think it looks better and is more safe to get images to tape more flat and saturate in post....
ash =o)
Bruce A. Christenson July 3rd, 2005, 11:44 PM Yessir....Scharky at DVXuser.com discovered that a bit of chroma blur in post does wonders for this.
Thanks, I will see what I can do with it in Vegas, it usually has the important effects!
Daniel Runyon July 4th, 2005, 02:15 AM Vegas is me weapon of choice....ye shall indeed find Chroma Blur amongst thine tools.
Barry Green July 4th, 2005, 05:11 AM Chroma Blur is an effect added in Vegas 5, so you'll need Vegas 5 or 6.
And this effect happens on all DV cameras, to the extent that the color is pure red or pure blue -- DV video has only 1/4 as much color resolution as it does luma resolution, so pure primary colors (red or blue mainly) will render at low, blocky resolution.. Some codecs do an automatic chroma blur (like Avid), some do none at all (like FCP). Michael Phillips of Avid posted a comparison of the difference between Apple and Avid's DV codec, and you can see how much smoother Avid's displays because of the chroma blurring they employ.
http://24p.com/codecs.htm
Evan C. King July 5th, 2005, 03:41 AM So Barry how do you fix that in FCP then?
Barry Green July 5th, 2005, 12:56 PM Never used FCP so I don't have a definitive answer.
Understand that the chroma blur is primarily beneficial for display on a computer. When you output back to DV all benefits of chroma blurring will be lost, as the footage will be re-decimated to 4:1:1. Going to DVD should still hold some improvement though, as chroma-blurred 4:1:1 should transfer to 4:2:0 better than raw 4:1:1 does.
For any and all image improvement in FCP, see Graeme Nattress' excellent lineup of image manipulation plug-ins etc. at www.nattress.com.
Ash Greyson July 5th, 2005, 01:41 PM Barry is correct... those great popping reds are hard to get to a medium. Gawd forbid you have something end up on VHS! YIKES!! I did one of the first major commerical products shot on DV back in 1997 and learned a lot the hard way. Of course, the cameras are better now but the red especially is a limitation of the format...
ash =o)
Joshua Provost July 5th, 2005, 05:23 PM Just to be clear, this is not a problem with the DVX100A, and would not be improved on the XL2. It is a result of the DV format's 4:1:1 color compression, and will be evident on all DV camcorders.
Chroma blur is one way to lessen the effect; intelligent deartifacting (such as Magic Bullet does) is another. Or, try a different format, such as DVCPRO, which stores more detailed color information.
Quick fix: Get the guy a different hat.
Charles Papert July 6th, 2005, 07:47 PM I have to disagree that this is purely a DV color sampling issue. From the first time I used the DVX I felt that the reds popped harder than other tones, and certainly more than I was used to with the XL1 series (which is known to be a warm-toned camera, generally indicating that it should deliver more saturated reds, yet it doesn't).
I have become used to adding a specific color correction filter in FCP to my DVX footage simply to desatured the primary reds to bring them in line with the other tones.
I've never gone so far as to compare color charts and do real testing on this--it's just my gut feeling about the images I have made with the camera.
Joshua Provost July 6th, 2005, 10:38 PM Charles, I agree with you on the defaults. However, if you increased the saturation on the XL2 and decreased it on the DVX100A, you'd transfer the problem from one to the other.
Everyone needs to understand their camera and set it accordingly, either to capture reality accurately, or achieve some artistic look. You can't rely on default settings. I'm sure you'd agree with that.
Ken Plotin July 7th, 2005, 10:12 AM I'm with Charles on this one. The DVX pops reds and oranges more than any DV/DVCAM I've ever used, including the XL1/s and Sony 200/A, 300, 150/170.
I use Vegas 4.0e and the free AaV6cc plug in to correct the red vector only.
Using the built in vectorscope, the uncorrected reds are WAY over 100.
As you drop the red saturation to about 85%, the detail in those oversaturated areas magically reappears. Definitely a quirk in a camera with otherwise excellent colorimetry.
Not to say that the DV format doesn't have color issues because of it's sampling, but this particular one does seem to be DVX specific.
Just my .02.
Ken
Ash Greyson July 7th, 2005, 02:55 PM This is my 10th year to shoot DV and I have shot with every camera imaginable and I can tell you this problem is more evident in the DVX than most cameras. It is indeed a general problem as noted above (particularly if you ever use a low shutter) but on the DVX it is worse.
The 1/3" CCD camera that has the most "legal" colors IMHO is the XL2. Film makers and people in general have become obsessed with the saturated look, so much so that a good clean image somehow seems milky or flat.
It is my preference to shoot the cleanest image as close to real life as possible and adjust in post.
ash =o)
Joshua Provost July 7th, 2005, 04:09 PM Ash, I'm with you on the point about shooting the cleanest image as possible. However, what cam gives an accurate image at it's default settings? They all need to be tweaked to better reflect reality. They all come out of the box over-saturated, over-sharp, and over-contrasty. Why would someone buy a $3-5k cam and just stick with the defaults? You pay more to get the manual control.
If someone pulls a DVX out the box, shoots something, then asks why they are seeing these artifacts, I put the blame squarely on the operator for not knowing his tools and properly adjusting the saturation (among other things). No offense to Bruce C. who started this thread.
I guess I am just of the blame the operator, don't blame the tool camp.
Charles Papert July 7th, 2005, 04:52 PM Josh: It's my (and apparently other's) contention that the issue is not of overall saturation, but of oversaturation of an individual channel, namely red. Although the DVX does have an impressive menu for a prosumer camera, it doesn't have complete color matrix control like its big brothers, and thus you can't bring down the saturation of the reds specifically (or I would have done just that).
Ash Greyson July 8th, 2005, 02:17 PM Indeed.... I do agree that the operator can overcome many of the issues but unless you desaturate everything on the DVX, the reds get flaming pretty easy. I think the XL2 handles reds excellent, best of the 1/3" cams.
The thing most people dont realize is the point I make over and over, a camera is a tool, an instrument if you will. Just because you have it, does not mean you have mastered it, or are even good at it. I am not a good musician, if I go buy a $3000 guitar, it does not mean I can play it like Eddie Van Halen...
ash =o)
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