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-   -   DVX100 Artifacts, Is this normal? (http://www.dvinfo.net/forum/panasonic-dvx-dvc-assistant/6140-dvx100-artifacts-normal.html)

Davi Dortas January 17th, 2003 06:54 PM

DVX100 Artifacts, Is this normal?
 
I'm experiencing extreme blockiness with footage shot with my DVX100. It appears during scenes with smooth continuous tone areas, like a shot of a wall lit with natural lighting. The colour blocks are huge! and they flicker randomly. I'm not sure if all DVX100s exhibit this problem because the footage is unacceptable for me, after it is rendered out of AE with colour correction or any type of image manipulation. I have not experienced this type of anomaly with footage shot with any other camera. It is hard to explain without showing samples. I built a web page that illustrates what I am talking about. Please take a look.

http://www.pigoinky.com/dvx100/

I encourage anyone who owns a DVX100 to run similar tests to see if you have the same issues. The final quality, for me, is totally unacceptable and I am seriously considering getting a refund on this camera. I shot an interview segment and noticed it during playback, where the interviewee was lit from a window and her surrounding was in 10% shade. The shaded areas exhibited an extreme amount of this "macroblocking" that was noticeable from the first generation. I haven't done exhaustive tests, but the tests so far have shown the DVX100 handling of smooth gradients to be abysmal.

Btw, I tried contacting Panasonic Technical support, but was unable to get through. I've heard horror stories of people trying to get technical support over the phone, so I'm bringing this issue to dvx100 members in hopes of figuring out the real issues to what I have been seeing.

Chris Hurd January 17th, 2003 07:36 PM

Judging from your example frames, I would want to diagnose this problem as contouring or gradient banding, which is common in shots of this type from prosumer digital video camcorders. The XL1 suffered from the same effect under certain conditions... see a three-part article on my website:

http://www.dvinfo.net/canon/articles/article10.php
http://www.dvinfo.net/canon/articles/article5.php
http://www.dvinfo.net/canon/articles/article18.php

If the DVX100 is implementing an 8-bit DSP, then it wouldn't surprise me if this is indeed a gradient banding issue. There is no fix; instead, one needs to take care not to shoot smooth continuous tone areas. For what it's worth, even high-end broadcast cameras can suffer from this, so it's not at all uncommon.

Nick Kerpchar January 17th, 2003 08:59 PM

Chris,
Thanks for the great info on contouring. If it's not one thing (audio synch with the DVX100) then its another (contouring with just about everyone).

Trying to make a final decision on which digital camcorder under $25,000 to get is like running a maze. For some of us, it's worse than buying a car!

BTW, you are one lucky person to be living in San Marcos. That place has got to be one of the best kept secrets in the U.S. Small university town, coeds, clear water river running through it (Frio? Guadalupe?), and easy access to Austin and San Antonio. Did I mention the Hill Country just minutes away? Beautiful, just plain beautiful.

Thanks again for the great info. Nick

Chris Hurd January 17th, 2003 09:27 PM

Thanks Nick, the river is the San Marcos River; it's headwaters come from a natural spring near the university. It's one of the cleanest rivers in the United States. Next time you watch Sam Peckinpah's "The Getaway," you'll see Steve McQueen jumping into it. San Marcos is a wonderful town still, despite the outrageous growth in the past decade or so. Where are you?

Skip Hunt January 17th, 2003 10:19 PM

I've had the DVX for over 2 months now and haven't noticed this problem. I've also not done the kind of extreme color correction you're doing, but I'd be curious if other cams do the same thing.

Chris, I've lived in Austin since 1989 and have never visited San Marcos. Anything worth seeing on a day trip? Did you end up getting a DVX? Or still working with a Canon?

Skip Hunt

Mark Nicholson January 17th, 2003 10:43 PM

I just did a similiar test, and while there is banding (as should be expected from an 8 bit source), I have no macro blocking.

Normal
http://home.inreach.com/bobinick/1normal.jpg

Equalize
http://home.inreach.com/bobinick/equalize.jpg

Joe Kowalski January 17th, 2003 11:02 PM

My test
 
Here's my test:

http://www.celout.com/dvx/

I can see the normal effects of DV compression, but nothing as extreme as Poojja's test.

Jeff Donald January 17th, 2003 11:37 PM

The banding and possible macro blocking will be more pronounced with a less colorful image . If you look at Poojja's images you'll see it has a fairly even shade of grey. Your choice of a more mixed color background will hide contouring, or banding.

Jeff

Davi Dortas January 18th, 2003 01:06 AM

Re: My test
 
OK I think there is something seriously wrong with my DVX100!! Your pics look so nice and they are so smooth, even telling are the equalized images. You have no extreme form of macroblocks that mine have. I re-did the same test, this time using a blue gelled light from a 10watt halogen. And sure enough, even with coloured lights, the banding is still there. I don't think this is banding, because the same scene shot with a GL-1 has none of those ugly macroblocks.

I re-did my test and have updated the web page with more pics.

http://www.pigoinky.com/dvx100/

I think there is a problem! :(


<<<-- Originally posted by Joe Kowalski : Here's my test:

http://www.celout.com/dvx/

I can see the normal effects of DV compression, but nothing as extreme as Poojja's test. -->>>

Jeff Donald January 18th, 2003 07:10 AM

Poojja,

Your comparisons are inconclusive because they are shot under different conditions, and are not even the same subject. If you want to do an accurate comparison then you must test cameras under identical conditions. Barring all that I do believe you have a problem with the blocking and all. Some banding is expected in an 8-bit device. Yours, however, seems to go beyond normal expectations.

If you want to do a valid comparison, I would suggest that other users shoot the dark blue portion of the sky. Barring some atmospheric conditions and pollution, everyones sky is lit pretty much the same. Then compare results. Random lighting and subjects will produce random results of little use.

Jeff

Nick Kerpchar January 18th, 2003 09:30 AM

Chris,
My wife and I currently live in Dickinson, Texas (between Houston and Galveston). My wife is from Austin and we lived there for the better part of 15 years during which time we attended and graduated from U.T. (liked it so much I graduated twice).

Yea, the San Marcos River. I was thinking of the river that runs through New Braunfels..... man, is that one ever cold!

Love this forum, thanks and Hook 'Em Horns. Nick

Chris Hurd January 18th, 2003 02:17 PM

Hi Nick -- lots of Texans on this board; some are displaced in other parts of the world... one big happy family here.

Skip -- the best time to visit San Marcos is when the University is in session; swing through Sewell Park by the river on a sunny day and you'll see what this town is all about.

Andre De Clercq January 19th, 2003 05:09 AM

Poojja, Can you test again without cine gamma?

Skip Hunt January 19th, 2003 09:23 AM

<<<-- Originally posted by Andre De Clercq : Poojja, Can you test again without cine gamma? -->>>

I too would like to see you repeat this test without cinegamma. Cinegamma yields some very interesting and nice results, but there seems to be a bit of strangeness that goes on with cinegamma selected under certain shooting conditions, particularly low-light.

BTW: where's Michael Pappas been hiding? He was all over the place joining the estatic DVX minions, but haven't seen him around the boards in weeks. Perhaps he's happily shooting? I shot some face closeups yesterday with the "THIN" vertical res setting, cam setup "0" IRE instead of 7.5, detail at "0", Cinegamma, 30p, etc. then color corrected, cropped and stretched in AfterEffects 5.5PB to widescreen 16:9. Then encoded to mpeg2 with high bitrate and quality, burned to DVD, projected from prog-scan DVD player via component cable to XGA LCD projector set to 16:9. I also did everything the same to the source footage except the cropping and stretching to 16:9 for comparison. The results were VERY good. The widescreen stuff looked fantastic. The only degradation I could see was a very slight softening from the crop and stretch. But, because I shot with the vertical detail on "THIN" and the detail set up to "0" from my usual preferred "-2", it basically balanced out and looked very, very good. I'd urge those of you with the same tools and a prog-scan player with large screen display, plasma, projector, etc. to try the same thing and let me know what you think.

Skip

Davi Dortas January 19th, 2003 09:46 AM

First thing Monday, I am going to return the DVX100 to my dealer to get new replacement. Joe K's test of his wall shot really did point out the problems I am having with my camera. Had I shot the exact same footage he did, I am pretty sure I would be getting the macroblocks. The problem is that the huge colour chunks occur anywhere there is a areas of the same colour, which means about 95% of my footage is affected.

Again, unacceptable. I haven't tried it with cinegamma off, but what would be the point in testing it. If it doesn't show artifacts with Cinegamma turned off, I still would not be happy NOT being able to use the cinegamma functions.

Panasonic should really look into this, because I am quite pissed with them right about now. All the footage that I have shot so far with this camera is flawed, and I don't know how I am going to hide these artifacts once I start editing it.


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