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ZERO NOISE PHOTOGRAPHY

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Offline kwf

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Re: ZERO NOISE PHOTOGRAPHY
« Reply #10 on: 21 / January / 2008, 09:49:09 »
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Quote from: ke7doy on 12 / January / 2008, 17:47:41
The flaw, it seems, might be that all of the copies will have identical noise and averaging them cannot cancel it. 

If the noise is "true" noise (e.g. photon noise, read-out noise) the noise will not be identical and averaging will reduce it. But I think you need about X^2 pictures to reduce the noise by an factor of X (16 photos to have a 1/4 noise). However most sensors will also have some amount of "fixed pattern noise", which e.g. is caused by impurities in the silicon, this can't be canceled by averaging. You can see some fixed pattern noise quite good by averaging many black pictures (thats the reason for the subtracting a black picture during long exposures. Another problem i heard of is that averaging to many pictures will increase the noise again, because you will have a greater chance to sample rare events (e.g. radioactive decay) which will bring you away from the true value again. Median instead of averaging filter is better then. But this is more a problem for extreme applications, like astrophotography, i think.

But i think real "ZERO NOISE" is an illusion.
« Last Edit: 21 / January / 2008, 09:57:55 by kwf »
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Offline lukg

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Re: ZERO NOISE PHOTOGRAPHY
« Reply #11 on: 23 / January / 2008, 06:13:02 »
mmm can I ask you how to blend images using photoshop?
Thank you!!

EDIT.: Ok I found out using Photomatix (batch processing-->average)....I would like to thank all of you (specially llinkawa) cause I didn't know this method (i'm a newbie photographer)...and it works very well. I tried shooting 8 jpeg at ISO 800, and my camera (s5) is horrible at such high ISO. But with this method pics are really good!!
Now I just need to wait the porting of Chdk for my cam and a simple script that takes multiple shoot with same settings.

Here's a sample.
The averaged pic:


100% crop of original ISO800:
http://img233.imageshack.us/img233/3637/iso800cropis3.jpg

100% crop of averaged pic:
http://img164.imageshack.us/img164/1046/avgcropxq7.jpg


Do you think that disabling Noise reduction (with CHDK) would be better or not? (and maybe applying noise reduction in post production after the blending process)
« Last Edit: 23 / January / 2008, 11:14:50 by lukg »
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Offline Barney Fife

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Re: ZERO NOISE PHOTOGRAPHY
« Reply #12 on: 24 / January / 2008, 00:50:25 »
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« Last Edit: 22 / April / 2008, 09:54:39 by Barney Fife »
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[acseven/admin commented out: please refrain from more direct offensive language to any user. FW complaints to me] I felt it imperative to withdraw my TOTAL participation. Nobody has my permission, nor the right, to reinstate MY posts. Make-do with my quoted text in others' replies only. Bye
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Offline lukg

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Re: ZERO NOISE PHOTOGRAPHY
« Reply #13 on: 24 / January / 2008, 06:32:10 »
Thanks Barney...i have a newbie question about shooting pics at night with less noise! what is better between -taking more pics at high ISO and then averaging or -using long exposures
(with tripod obviously)

Thanks.
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Offline Barney Fife

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Re: ZERO NOISE PHOTOGRAPHY
« Reply #14 on: 24 / January / 2008, 07:26:53 »
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« Last Edit: 22 / April / 2008, 09:55:01 by Barney Fife »
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[acseven/admin commented out: please refrain from more direct offensive language to any user. FW complaints to me] I felt it imperative to withdraw my TOTAL participation. Nobody has my permission, nor the right, to reinstate MY posts. Make-do with my quoted text in others' replies only. Bye
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Offline a710is

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Re: ZERO NOISE PHOTOGRAPHY
« Reply #15 on: 24 / January / 2008, 07:58:45 »
I believe that especially on an IS enabled camera long exposures at low ISOs are the winners.
I have taken many pictures at 1-2s exposures handheld (I don't even own a tripod) that are totally sharp. they're awesome.
I mean of course some will come out nasty but if let's say I wanna have a good picture with a long exposure I set the camera to continuous, wait for the lens to stabilise and then I shoot let's say 10 pics holding the camera as steady as possible.
I then go to play mode, zoom in to a section of the pic to see the individual pixels and then press set so that the camera zooms to the same section of every pic as I switch back and forth. I delete the shaken pictures and only keep the good ones.
that means card space economy and less effort.

so I believe that for IS cameras, averaging is good only in particular situations (like the star shooting mentioned by Barney). for non-IS cameras averaging may be more useful.
« Last Edit: 24 / January / 2008, 08:00:51 by a710is »
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Offline lukg

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Re: ZERO NOISE PHOTOGRAPHY
« Reply #16 on: 24 / January / 2008, 08:10:24 »
Thank you very much Barney and 710is...I'm gonna try to experiment asap! And yes, I meant about shooting still subjects at night like monuments, bridges, buildings...no stars, no moon :D
Unfortunately, even with IS i can't obtain by hand what I want at night (without the flash obviously), so I usually disable it at night and use a tripod.
My last question...about aperture, does it influence the amount of noise? Or in other words...for my subjects what is better between shooting with long exposures at F2.8 or very long exposures at F8? (don't consider the depth of field, consider only image quality)
Thank you and sorry if i bother you.

EDIT: I've made a quick test...and it's very difficult to me obtain, by hand, sharp image with IS activated for exposure longer than 1" (not impossible, but i need to shoot 3 or 4 to obtain a good one).
So in this situation it's better for me to take multiple high ISO pics.
I must try with tripod and at night!!
« Last Edit: 24 / January / 2008, 08:26:28 by lukg »
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Offline a710is

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Re: ZERO NOISE PHOTOGRAPHY
« Reply #17 on: 24 / January / 2008, 10:03:17 »
here are some pics I made one night in my town. all ISO80 jpg handheld (it was freezing too :D ) with IS enabled.
I've taken them fullsize but uploaded them downsized to 1600 x 1200. I believe noise reduction was set to auto
« Last Edit: 14 / July / 2008, 03:10:01 by a710is »
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Offline lukg

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Re: ZERO NOISE PHOTOGRAPHY
« Reply #18 on: 24 / January / 2008, 10:49:41 »
Nice pics!! Then it should be a problem in my hands :D :D
or maybe it's my S5 and its ~500gr :D :D
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Offline a710is

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Re: ZERO NOISE PHOTOGRAPHY
« Reply #19 on: 24 / January / 2008, 11:08:22 »
it should be even more stable cause it's got more inertia :D
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