HG10 "fixed pattern" noise on dark shots at DVinfo.net

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Canon VIXIA Series AVCHD and HDV Camcorders
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Old November 23rd, 2007, 12:07 PM   #1
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HG10 "fixed pattern" noise on dark shots

My HG10 has fairly noticeable fixed pattern noise at low light.
Fixed pattern noise is this: A type of noise that is the same frame after frame. So when you pan a shot across a dark background, the noise stays there as if you had a dirty screen or sensor. It does not move or twinkle like normal noise.
I have a feeling that all HG10s have this, but I'm not sure. FPN can be calibrated out, but Canon may have not done this.
Shooting conditions I noticed it on: 24P 1/24 sec in shadows in a night city street shot. Slow pan. Look in shadows near black. The HV20 may also do this, since they share sensor types.
Any one else notice this?
I can come up with a filter to fix this
-Les
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Old November 23rd, 2007, 12:22 PM   #2
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Isn't that normal for AVCHD cameras? It sounds like normal temporal noise reduction. IE, it doesn't change pixels that don't change enough between frames. The downside is that there will be ghost images if the noise reduction is set too high.
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Old November 23rd, 2007, 12:39 PM   #3
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It's noise not compression blocking. The compression blocking is there as well, on top of the fixed pattern noise. The FPN is much more noticeable than the compression effects. In fact, the AVCHD compression is doing a swell job of preserving the dark FPN I am talking about !

I know most people will not be shooting in dark conditions much, and most users probably wont see this issue, but users at this forum are a bit more demanding.



Quote:
Originally Posted by Mikko Lopponen View Post
Isn't that normal for AVCHD cameras? It sounds like normal temporal noise reduction. IE, it doesn't change pixels that don't change enough between frames. The downside is that there will be ghost images if the noise reduction is set too high.
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Old November 27th, 2007, 08:01 PM   #4
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so is there a post-fix for this? I just recently shot a winter show in a night club and I have fixed noise (more prominent in shadows).
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Old November 28th, 2007, 12:48 AM   #5
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Yes, there is a way to fix it, you make a picture of the dark pattern with the camera pointing at black, or near black. Saving that image, you subtract that image from the moving video image, tuning it with a luminance keyer to only effect the blacks. That should get rid of most of it.
Too bad Canon doesn't do this themselves as you shoot, it's not that hard to do compared to compression.
-Les
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Old November 28th, 2007, 07:37 AM   #6
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There is also the Neat video filter. http://www.neatvideo.com/examples.html

Ron Evans
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Old November 28th, 2007, 08:58 AM   #7
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wow, the neat video filter works pretty well! thanks for the input guys!
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Old November 28th, 2007, 02:49 PM   #8
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Neat video works on random noise. fixed pattern noise is not distinguishable from real image detail without special input of a dark only frame.

Example: Say the FPN looks like a brick wall pattern. Now shoot video of a brick wall. How does the filter know the difference between the brick wall and the FPN ? It does not. It would remove the brick wall pattern and leave you with a blank screen!

The filter has to have prior image data of the FPN ( the dark image ).
Neat Video is a good filter for random noise, for sure.
-Les
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Old November 28th, 2007, 03:21 PM   #9
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It is my understanding that Neat builds a profile...
"Neat Video builds and uses device noise profiles to make noise reduction custom-tailored to video capturing device
A device noise profile is a reusable analysis of noise properties of a video capturing device (digital video camera, film digitizer, etc.) working in a certain mode. Using a noise profile for a video capturing device in effect makes noise reduction custom-tailored to this device. Neat Video can automatically build noise profiles by analyzing the input video data."

Ron Evans
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Old November 28th, 2007, 09:29 PM   #10
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The profile has no spacial information, it's only for random noise.
It does a great job of removing the random noise, leaving the fixed pattern ( non random ) there, now
the fixed pattern is even more noticeable, since it does not get masked by the random video noise.

-Les


Quote:
Originally Posted by Ron Evans View Post
It is my understanding that Neat builds a profile...
"Neat Video builds and uses device noise profiles to make noise reduction custom-tailored to video capturing device
A device noise profile is a reusable analysis of noise properties of a video capturing device (digital video camera, film digitizer, etc.) working in a certain mode. Using a noise profile for a video capturing device in effect makes noise reduction custom-tailored to this device. Neat Video can automatically build noise profiles by analyzing the input video data."

Ron Evans

Last edited by Les Dit; November 29th, 2007 at 12:43 AM.
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