Noise

[Jaimie Blake]

Hello All!

 

I have a question about video and color noise.

 

I got these definitions from the Kodak website, but I do not totally understand them.

 

Here is the one for video noise...

 

"More commonly called "luminance signal-to-noise ratio." This is a measure of how pure the video signal is (the monochrome or black-and-white portion of the picture). Tapes with good luminance signal-to-noise ratios have sharper, clearer images. This property has even greater importance on multiple generation copies."

 

And here is the one for color noise...

 

 

"Better known as chrominance signal-to-noise ratio. A measure of how accurately the color signals are reproduced. Poor chroma signal-to-noise ratios are evidenced in color fringing on edges of objects and what appears to be thousands of moving dots in large areas of highly saturated colors (especially red).

 

I understand that noise lowers the image quality, but I don't how to differentiate the difference between noise and other video issues. I would really like to recognize it if I saw it and not mistake it for something else. So, if someone would please expound a little bit on these definitions in simpler terms and refer me to a picture of each I would appreciate it. Also, is noise restricted to video or can film be affected as well?

 

 

Thanks!

:D

[David Mullen ASC]

To really judge noise it has to be a moving image -- it's harder to see in a still frame although possible. It's a little like grain in that regard.

 

Noise is an electronic effect and only relates to film in that a film-to-video transfer can have noise in it as well as grain, which is a film attribute.

 

Hard to describe the difference -- grain sort of swirls slower while noise sort of shimmers and sparkles faster. In a sense, grain seems to move around while noise seems to be more locked in position.

[Jaimie Blake]

Thank you for responding so quickly!

 

Can you please tell me what causes noise? Is it poor tape quality or does it have to do with camera settings? How is it remedied?

 

Thanks!

:)

[David Mullen ASC]

Lots of things can cause noise... misexposure, color-correction decisions, recording format, camera settings, etc. Some cameras are simply noisier than others.

 

There are noise-reduction software solutions, but they often cause the image to get softer.

[Jaimie Blake]

Thanks so much for the info. It helped lot!

:D

[Laurent Andrieux]

Noise is due to electronic circuitry. It actually adds some electric value to your signal that is not especially related to it, a random way. Best way to see it is in the darkest areas of an image. When it's black, you should have no electronic signal, but when there is noise, the black is not black, but becomes slightly grey. The proportion of it to the signal is the signal/noise ratio.

 

A good way to enhance it is to push electronic gain on a video camera, you will easily see it. If you have a TV monitor, unplug the antenna cable a bit, like if the contact was not correct, it will automatically generate noise on your tv set since the Automatic Gain Control circuitry will then turn on.

 

You see some "snow" on the scren. That's video noise. On an audio signal, it is the same problem, and sounds like a "shhhhh"

[Jaimie Blake]

Thanks Laurent!

 

I will push the gain on my camera so I can get a firsthand look.

 

Very helpful!

 

One more question - is noise only initiated when the camera is recording, or can it happen after the recording when the video is transferred to a computer?

 

Thanks!

 

:D

[Laurent Andrieux]

Noise can be generated at any step... but a pure dugital link should not generate noise (it actually does but is pointless as the information is treated). It is more a analogic problem than a digital problem. But 1) Mind that a lot of processes that seem to only involve digital processes actually invove analogic ones as well 2) That treating a digital signal can add some noise, when you grade an image on a station for instance.

 

The only point of acquiring an image through a digital link like IEEE or SDI should not provide noise.

[Dino Giammattei]

I believe that the difference between a 5k camera and a 50k camera is not only the amount of noise, but how the manufacturer deals with it. In pro-sumer gear, where most of the peaking, contrast, and clipper controls are automatic, there is only so much you can do. In higher end cameras there are more ways to tweak the picture to manage noise.

After years using an Arriflex 16mm, the change to video meant suffering through using the venerable but flawed RCA TK76, followed by early NEC, and Sony CCD products. I had almost given up hope of ever making beautiful pictures again. It was then that I was fortunate enough to have the opportunity to work with a BTS,LDK91. It was by no means an overly quiet camera. Most of the Sony, Panasonic, and JVC products had better S/N specs. If I'm not mistaken, it was the only camera on the market at the time that didn't use Sony FIT CCD's. The people at Phillips, using IT chips of their own design, had somehow managed to make the noise appear softer while still getting eight hundred lines of resolution. The resulting picture had wonderful mid-tone detail that was flattering to flesh tones, and had virtually none any of the artificial peaking that I saw in the Sony cameras. It didn't have that sterile video look, rather, the pictures had a beautiful patina that you enjoyed looking at. (The program Night Court was shot with the older LDK90).

Most of my recent work has been with a BVW600, which is a great looking camera that also deals well with noise. Sadly, management decided to go cheaply into digital, and now I'm struggling to get my look with DvCam. It's hard being a dinosaur? dinog

[Dino Giammattei]

I believe that the difference between a 5k camera and a 50k camera is not only the amount of noise, but how the manufacturer deals with it. In pro-sumer gear, where most of the peaking, contrast, and clipper controls are automatic, there is only so much you can do. In higher end cameras there are more ways to tweak the picture to manage noise.

After years using an Arriflex 16mm, the change to video meant suffering through using the venerable but flawed RCA TK76, followed by early NEC, and Sony CCD products. I had almost given up hope of ever making beautiful pictures again. It was then that I was fortunate enough to have the opportunity to work with a BTS,LDK91. It was by no means an overly quiet camera. Most of the Sony, Panasonic, and JVC products had better S/N specs. If I'm not mistaken, it was the only camera on the market at the time that didn't use Sony FIT CCD's. The people at Phillips, using IT chips of their own design, had somehow managed to make the noise appear softer while still getting eight hundred lines of resolution. The resulting picture had wonderful mid-tone detail that was flattering to flesh tones, and had virtually none any of the artificial peaking that I saw in the Sony cameras. It didn't have that sterile video look, rather, the pictures had a beautiful patina that you enjoyed looking at. (The program Night Court was shot with the older LDK90).

Most of my recent work has been with a BVW600, which is a great looking camera that also deals well with noise. Sadly, management decided to go cheaply into digital, and now I'm struggling to get my look with DvCam. It's hard being a dinosaur? dinog