Blue Noise In Dark Areas

MUTTLEY wrote on 1/25/2004, 2:32 AM
Blue Noise In Dark Areas

Pretty sure you know what I'm talking about. Any advice for this ? Or any tutorials that ya know if ? This drives me crazy. I've messed with color correction till I was myself blue in the face but have yet to find the magic formula. Perhaps I just don't have the grasp on color correction that I thought I had. I'm a helloffa lot better at fixing up an bad image in Photoshop than I am fixing video in Vegas.

Any experience with the matter would be greatly appreciated.

- Ray

www.undergroundplanet.com

Comments

farss wrote on 1/25/2004, 2:58 AM
Well there's no magic bullet to get rid of it once it's shot. Black restore can help or color curves to push the blacks down a bit. Problem is you are then crushing the blacks so you are affecting the rest of the image as well.
As a matter of interest what's the material come off?
If its from VHS then processing in the analogue domain can help.
MUTTLEY wrote on 1/25/2004, 5:10 AM
Its footage that I shot at night with my XL1. Was an interview on a porch. The subject looks great, background ... not so great.

- Ray

www.undergroundplanet.com

JJKizak wrote on 1/25/2004, 5:51 AM
The problem is the low light level shooting. Boost the contrast up to blow the background to total dark if possible so you just see the faces and the people. This will mess with the faces so you have to compromise. The contrast will darken the pixelation to almost black. This is one perfect example of why people still favor film. There might be other ways but I am just a novice. You have to be looking at your tv monitor while doing this, not the computer monitor.

JJK
farss wrote on 1/25/2004, 6:13 AM
If he was shooting on film he would have needed an aweful lot more light in which case he wouldn't have had the problem to start with or else the stock would have been pushed so much that the grain would make it look probably even worse than how it turned out on the video.
Film has many advantages over video. Not the least of them being that it costs a fortune so you spend the extra money to get everything else right as well.
PeterWright wrote on 1/25/2004, 6:19 AM
If the subject is relatively still within the frame, you could double up the event on two tracks, apply a soft edged cookie cutter or mask to separate the subject, then just apply curves, contrast, blur or whatever to the background so that this can be made more solid without affecting the subject.
farss wrote on 1/25/2004, 6:24 AM
Few things to learn.
Shooting with a black background isn't a good idea, video just doesn't handle that much contrast well.
Probably you didn't have enough light on the subject to start with, it's just that the noise is much more noticeable in the blacks. If you did have enough light on the subject the you'd need to either use manual exposure or switch the camera into Spotlight mode or your subject will be too hot.

None of this helps with the immediate problem. You can try contrast as has been suggested although that's a pretty blunt tool. Color curves (selecting all colors) lets you control the gamma. Putting a flat spot at the bottom of the curve will keep anyhting below a certain level as black. From my experience though you can only push that so far before you affect the subject as well.

The median filter may help by averaging out the noise, you will get some loss of resolution and very long render times though.

As i said there's no magic bullet, if there was it'd be in camera DSP chips.
MUTTLEY wrote on 1/25/2004, 11:49 AM
Color curves did the trick. A little darker than I would prefer, but a much cleaner look.

Baicly brought down the low on the blue chanel, bumped up the red and green high end a bit. Looks a whole lot better, a whole whole lot better.

As always, a humble thanks.

- Ray

www.undergroundplanet.com

earthrisers wrote on 1/25/2004, 4:52 PM
This is not a technically helpful comment, but:

This topic-name sounds like a great name for a band.
PeterWright wrote on 1/25/2004, 5:48 PM
Nice one, earthrisers ;)
Acts7 wrote on 1/25/2004, 7:46 PM
compensate for the low light "noise" by applying a low level gausian blur in the blue channel of the video in post (that's a tip kids. Try it. Low light noise is almost exclusively in the blue channel. Blur that and, if needed, apply contrast in the green)
craftech wrote on 1/26/2004, 5:16 AM
that's a tip kids. Try it
----------------------------------
Thanks pop I will.

John
Acts7 wrote on 1/26/2004, 8:06 PM
dang you make me feel old
Pop?
Im only 27
I couldnt remember where I found that quote but I was so excited when I did find it that I emailed the quote to myself
MUTTLEY wrote on 1/28/2004, 6:53 PM
How do you add contrast just to the green ?

- Ray

www.undergroundplanet.com