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Night photo: 64 averaged RAW photos (noise reduction)

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Offline avatorl

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Night photo: 64 averaged RAW photos (noise reduction)
« on: 29 / April / 2008, 18:05:36 »
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1.jpg = crop of a photo #1 (RAW, ISO=80, Av=2.7 Tv=20s)
64.jpg = crop of a photo from merged (averaged) photos ##1-64 (RAW, ISO=80, Av=2.7 Tv=20s)

Camera: Canon S3 IS+CHDK Allbest v.50
« Last Edit: 29 / April / 2008, 18:10:19 by avatorl »
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Offline lukg

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Re: Night photo: 64 averaged RAW photos (noise reduction)
« Reply #1 on: 29 / April / 2008, 19:51:59 »
Imho, you could have raised ISO and take less pictures. I think averaging can handle high iso noise better than long-time exposure noise! I think ISO noise follows a better "random" distribution.
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Offline avatorl

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Re: Night photo: 64 averaged RAW photos (noise reduction)
« Reply #2 on: 29 / April / 2008, 20:04:58 »
Quote from: lukg on 29 / April / 2008, 19:51:59
Imho, you could have raised ISO and take less pictures. I think averaging can handle high iso noise better than long-time exposure noise! I think ISO noise follows a better "random" distribution.
Thanks, I'll try high ISO tonight. I thought about it, but yesterday I set low ISO to test not only noise reduction, but timelaps video in addition (YouTube - Timelapse) I think that low ISO and long-time exposure noise is less than high ISO and short-time exposure noise, isn't it? So, I used low ISO to shoot each single picture with a less noise, to use it in my video.
« Last Edit: 30 / April / 2008, 02:40:31 by avatorl »
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Offline mrproper

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Re: Night photo: 64 averaged RAW photos (noise reduction)
« Reply #3 on: 29 / April / 2008, 20:10:30 »
Aaah... the wonderful view of matchbox apartment buildings :)

Nice results, except for the over-exposed light areas :(
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Offline avatorl

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Re: Night photo: 64 averaged RAW photos (noise reduction)
« Reply #4 on: 30 / April / 2008, 14:45:05 »
Quote from: lukg on 29 / April / 2008, 19:51:59
Imho, you could have raised ISO and take less pictures. I think averaging can handle high iso noise better than long-time exposure noise! I think ISO noise follows a better "random" distribution.
I have just finished my experiment: averaging of 16 photos with ISO=80 Tv=10" give a less noise picture, then averaging of 16 photos with ISO=400 Tv=2" or with ISO=800 Tv=1"/
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Offline lukg

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Re: Night photo: 64 averaged RAW photos (noise reduction)
« Reply #5 on: 30 / April / 2008, 14:50:19 »
Quote from: avatorl on 29 / April / 2008, 20:04:58

Thanks, I'll try high ISO tonight. I thought about it, but yesterday I set low ISO to test not only noise reduction, but timelaps video in addition I think that low ISO and long-time exposure noise is less than high ISO and short-time exposure noise, isn't it? So, I used low ISO to shoot each single picture with a less noise, to use it in my video.

I think you did well, then!
About High ISO, hope to see your pictures soon! I'm curious to see if high iso had a reason to exist (by averaging).
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Offline lukg

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Re: Night photo: 64 averaged RAW photos (noise reduction)
« Reply #6 on: 30 / April / 2008, 15:08:10 »
Quote from: avatorl on 30 / April / 2008, 14:45:05
Quote from: lukg on 29 / April / 2008, 19:51:59
Imho, you could have raised ISO and take less pictures. I think averaging can handle high iso noise better than long-time exposure noise! I think ISO noise follows a better "random" distribution.
I have just finished my experiment: averaging of 16 photos with ISO=80 Tv=10" give a less noise picture, then averaging of 16 photos with ISO=400 Tv=2" or with ISO=800 Tv=1"/

Mmm, you cannot compare 16 pics at ISO80 with only 16 pics at ISO400.
But maybe you can compare results with 64 pics (too much for me, but maybe not for you) at ISO80 and 32 at iso400, since 32pics could be enough to remove the noise due to iso 400, and leave better details....I don't know, I'm just guessing :D
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Offline avatorl

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Re: Night photo: 64 averaged RAW photos (noise reduction)
« Reply #7 on: 30 / April / 2008, 17:26:18 »
Quote from: lukg on 29 / April / 2008, 19:51:59
I think averaging can handle high iso noise better than long-time exposure noise! I think ISO noise follows a better "random" distribution.
Look, we have ISO noise (random noise) + fixed pattern noise. But "fixed pattern noise" could be reduced by dark subtraction well. So, the only problem is a random noise that influenced by ISO.
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Offline lukg

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Re: Night photo: 64 averaged RAW photos (noise reduction)
« Reply #8 on: 30 / April / 2008, 18:52:25 »
Quote from: avatorl on 30 / April / 2008, 17:26:18
Quote from: lukg on 29 / April / 2008, 19:51:59
I think averaging can handle high iso noise better than long-time exposure noise! I think ISO noise follows a better "random" distribution.
Look, we have ISO noise (random noise) + fixed pattern noise. But "fixed pattern noise" could be reduced by dark subtraction well. So, the only problem is a random noise that influenced by ISO.

What I meant is: long exposure in my experience gives of course very low random noise, but it saturates colors and blurs details. Averaging 64 (too many for me) iso80 pics gives a noise free (random noise) image but with poor details (like a cartoon).
Using high iso, you have the advantage that the photosensitive element is not overcharged, with the disadvantage that half of the pixel (for example), is noise. But thankfully this noise is different from pic to pic, so averaging more high iso pictures has more sense and preserve better details.
Fixed noise is another matter.
Since i've never taken so many pics for averaging, i was just curious to see the differences between a noise free picture obtained by averaging long exposure pictures, and a noise free picture obtained by averaging high iso pictures.
« Last Edit: 30 / April / 2008, 19:04:31 by lukg »
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Offline avatorl

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Re: Night photo: 64 averaged RAW photos (noise reduction)
« Reply #9 on: 01 / May / 2008, 02:31:03 »
ISO80 T=10" 16 RAWs
ISO400 T=2" 16 RAWs
ISO800 T=1" 16 RAWs
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