HVX200 video noise

[Noah Kadner]

Post a still- typically noise comes from underexposure and/or too much contrast.

Noah

[Ken Nemetchek]

Noah:

Sorry about the delay, but my web person is out of town.

You can get the image at

https://www.abvc.ca/pics/videonoise.tif

or

https://www.abvc.ca/pics/videonoise.tga

The .tga image is as directly output from the fcp timeline (no filters were added), and the .tif is derived from that.

Although the still doesn’t look too bad on its own, when the sequence plays (there is a pan following the tractor), the sky has a lot of obvious noise.

Again, I am looking for strategies in dealing with this issue, and not in complaining about the camera – which in general terms I absolutely love.

Thanks for any coucil you may be able to offer.

Ken Nemetchek

Alberta Visual Communications

[Gary Adcock]

[Ken Nemetchek] “Again, I am looking for strategies in dealing with this issue, and not in complaining about the camera – which in general terms I absolutely love.”

Use the simple solution that all still photographers use.

go to video filters> channel > channel blur
and blur only the blue channel — try a something between 2-10 pixels to start ( EXPERIMENT!!!! )
for overall noise reduction blur just the green channel start with something less than 5 pixels.

This is the same process digital still shooters use to reduce image noise.
your results will vary every single time!
Make sure you test every shot you try this on.

gary adcock
Studio37
HD & Film Consultation
Post and Production Workflows
Chicago, IL
gary@studio37.com

[Noah Kadner]

It’s always a little hard to judge things like gamma from stills but to be honest these shots look a bit underexposed- maybe a stop or half a stop. Also- are you using the factory presets for your scene files or have you adjusted your gamma and knee settings?

Noah

[Ken Nemetchek]

Noah:

I did shoot with the #1 scene file, with no changes to the factory settings.

I pulled up the original in fcp and this frame did top out at about 70% on the waveform – I assume that the waveform at 100% in fcp is on par with the 100% zebra on the camera. I watched the entire clip and found the following: the cab of the tractor averaged between 70 & 80; the clip peaked at 90; and the sky averaged about 45, although it varied slightly as the shot continued, ending at about 42.

Now, on the day I usually try to open the iris until the zebra stripes appear and then dial down slightly. If that is the trick, then so be it. My logic is that I will always colour time anyway, so why not see the most in the shadows by exposing as bright as I can, right? Anyway, if the shot is simply underexposed, does that mean a properly exposed shot doesn’t get this video noise, or simply hide it better? Seems to me a curious thing.

With the advice Gary gave me (by the way, thanks very much for that, Gary), I figure that I might be on the right track. If there are a few additional nuggets of wisdom you each can share, I would very much appreciate it.

Ken Nemetchek

Alberta Visual Communications

[Alex Viarnes]

You really can’t judge video from stills.. having said that, The image is underexposed, at least on my Mac. The noise looks about normal for 1/3 inch camera; doesn’t look bad as far as noise goes. As for blurring channels….I would never do that.
Aloha
-A

[Gary Adcock]

[alex viarnes] “As for blurring channels….I would never do that.”

Thats why experimentation is needed.

It has been a standard process since the beginning of the digital still revolution. Companies like Nik Multimedia and Alien Skin have built entire filters sets around the concept.

gary adcock
Studio37
HD & Film Consultation
Post and Production Workflows
Chicago, IL
gary@studio37.com

[Jan Crittenden livingston]

Hi,

This shot is under exposed. That said, you need to be aware that you have 2 zebras in your camera. The first one you see is preset from the factory to be 80 ire and the second one which shows in the VF in the opposite direction is set for 100 ire. So from looking at this picture you made an adjustment and exposed your white area at about 70-75 ire assuming that the zebra you were seeing was 100 ire. If you do not want to work with 2 zebras, as they can be confusing you can turn one off, but you have to go to the menus to do that.

However if you want to use the power of 2 zebras, you can use Zebra 1 for skin tone, and Zebra 2 for Highlights. Bracket between. Zebra 1 can actually go down to 50 ire and thus can give you feed back about the more shadowy areas of your picture, but that may be too much of a good thing.

Anyhow, I hope this helps you.

Best,

Jan

Jan Crittenden Livingston
Product Manager, DVCPRO, DVCPRO50, AG-DVX100
Panasonic Broadcast & TV Systems

[Alex Viarnes]

On the photography side I have been all digital since 1990 when I got my first digital back (4megapixel). I currently shoot with a 39mp back and in all those years of manipulating pixels I’ve blurred chanels only for a special effects. I have always found the filter sets you mention gimicky and never as good as what you can achieve with photoshop.Yes, experimentation is essential in all art forms and while blurring chanels on high resolution stills can reduce noise doing so on video, in my opinion is a very bad idea.
Aloha
-A

[Ken Nemetchek]

Alex:

I did some experimentation on blurring the pixels in the blue channel, but I didn’t find the results satisfactory.

That said, are there tools that can average a given pixel location over several frames? It seems to me that this would be able to get rid of noise better than simply blurring a channel. When I blurred the blue on the frame I posted, I found that the colours in the tractor cab shifted, resulting in a yellow halo on the edges of the white.

Or am I in a position where I just need to make sure that the footage I shoot are exposed higher, in terms of IRE?

A further thought occurs to me: is at least part of this simply an issue of the camera being 8 bit, and so it can’t handle the subtle grad in the sky?

Let me just say that I am very thankful for all of the input given me on this topic by so many of you. Thanks.

Ken Nemetchek

Alberta Visual Communications