Red Vertical Banding in DVX100B - Does it need repair?

C

catalyst

Member
Hello,

I started noticing this in a recent stage production I taped. I thought it was a fluke or something.

I've taped a wedding since then, and the issue appeared there, too. Look at the red dresses. The problem is most pronounced at the edges, but is visible even in the centers. When viewed in motion, the person in the red dress looks like she's stepped in to a filter of somekind that basically says, "pixelate me".

Please have a look at the two linked images below and let me know if this is normal (I don't think so), if there's something I've got set wrong, or if you think this is an issue that will require a repair of some kind. Also, since I've not had any experience with getting service on a unit like this from Panasonic, what kind of experience should I expect if I need to send it back (NJ), eg turnaround, etc?

Thanks,

Catalyst

http://www.catalystdigitalstudios.com/RB1.jpg
http://www.catalystdigitalstudios.com/RB2.jpg
 
Not sure how to answer, but...

Not sure how to answer, but...

Hello,

I don't think I've changed anything (using menus, for example) from the factory defaults. I was probably shooting all AUTO, using Preset 1 (60i), gain set to "L". What other settings information do you have in mind?

Thanks,

Catalyst

bwest said:
what are your settings?
Click to expand...
 
this looks like a capture problem that i sometimes suffer from as well.

every fourth and fifth frame, or maybe just every fifth, becomes completely interlaced looking. No way to fix this except to recapture me thinks.
 
I'm actualy having the same problem with my project (shot on a DVX100b) except it isn't happening on every fourth or fifth frame, it's consistent all the way through in certain areas. My source footage looks clean as well as the capture files. Its when it is brought into FCP I get this problem. Something in the capture settings maybe?
 
Well the interlace is one thing. I will assume you know that's the format you were shooting in.

The red pixelation is a well known problem with the DV codec and it is not a malfunction of the camera. Really bright saturated colors are a problem for DV due to the 4:1:1 color space. To fix it, in post add a "chroma blur" filter and it will fix the problem.
 
Yep, completely normal for any miniDV camera. Chroma blur can help a little, but when you encode for DVD, it gets put right back in a limited color space. It usually doesn't look as bad on TV/DVD playback compared with looking at still frames. DVX's and other miniDV cameras used on broadcast programs all the time, and you don't notice the problem.
 
William, I'm getting this same problem in more pesky areas like actors' faces, check out this link.

http://www.flickr.com/photos/7203400@N08/846649234/

You may have to double size it to see the vertical lines on his face. Do you know if this chroma blur filter will fix it without muddling the actors face?

Also, should I apply this in FCP or in after effects where I'm bringing the final export to anyway?

Thanks for your thoughts on this.

-Sergio
 
Yea it looks more like an interlace problem than a color bleeding issue... strange look?
will it do this in progressive as well?
 
Nope, that is the same chroma problem (2nd picture). A chroma blur will fix this as well. Apply in AE if you are exporting from FCP. (if you are doing your grading/cc in AE)
 
William_Robinette said:
Nope, that is the same chroma problem (2nd picture). A chroma blur will fix this as well. Apply in AE if you are exporting from FCP. (if you are doing your grading/cc in AE)
Click to expand...


Yea, I see it now, after enlarging it, its the same thing. I take it this comes from low light levels, or is greatly excaserbated by low light levels?
 
Thanks William! I tried this out on AECS3 and didn't see anything referred to in the filter list as a chroma blur, I did get the channel blur filter to produce good results, is that the same thing? Sorry, this might be a totally noob question but I need to know.
 
It Worked Great! Thanks! (now, where to learn more?)

It Worked Great! Thanks! (now, where to learn more?)

Hello,

Thank you VERY MUCH for this post; thanks to others also for very helpful points on this. I applied the FCP Color Smoothing Filter and it made a significant difference. Then I hunted down Adam Wilt's H. Chroma Blur filter (which is adjustable); even better! Wow!

OK, so now that I feel clueless (but a bit less), does anyone have any suggestions for good sources to learn about these basic issues with DV? For those of you who know the "Missing Manual" series, are there any books/sites that read like that, but for DV?

Thanks!

Catalyst

William_Robinette said:
Well the interlace is one thing. I will assume you know that's the format you were shooting in.

The red pixelation is a well known problem with the DV codec and it is not a malfunction of the camera. Really bright saturated colors are a problem for DV due to the 4:1:1 color space. To fix it, in post add a "chroma blur" filter and it will fix the problem.
Click to expand...
 
this 4:1:1/4:2:0 colour space and bad dv codec sounds like a bad excuse to me, we are talking extreme pixelisation with anything that is red, occurring not only at the extreme edges of a red with say a green but in and amongst other reds, and only with reds!
the blurring fix does smooth it out, but it also blurs the image... ie. not fixing it.
how come virtualdub does not pixelate the reds? how comes it seemingly handles the codec and the colour spacing correctly?

500% magnification of the examples i posted above.

vegas - http://myweb.tiscali.co.uk/bbiproductions/vegasx5.jpg

virtualdub - http://myweb.tiscali.co.uk/bbiproductions/vdubx5.jpg
 
Last edited:
Without knowing (or using Vdub) it is possible that it is applying some sort or chroma blur to the footage if it is working with it in some sort of uncompressed timeline or color space.

I.E. It might be doing something to the footage under the hood that you would manually do in Vegas.

Just a guess though.
 
funny, how both examples appear to be low light again?
I read many programs have the auto-blur...example Avid
 
at first i thought maybe vdub was applying some filter... ive asked on their forums to see if anyone can shed some light on it. BUT, i tried adding a chroma blur in vegas, and all it did was blur the image slightly, it hardly made a dent in the blocking, just gave me a worse picture over all, this is, after all, some extreme test footage i shot , right? very low light and completly red. ...so if virtual dub is applying a filter it is doing so without causing any real deteriation to the image and removing the blocking down to what one would expect from a 4:2:0 colour space compression. pretty good.

but the thing is virtual dub is so basic (its like 1.09 megs fully installed) that i doubt its applying any special magic at all. i think its just handling the codec better, or maybe using one of its own, or something!

what ever the cause, if the free open source vdub can do it the $$££ vegas and others should be able to do it too.
 
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