raw average from a single raw picture? - RAW Shooting and Processing - CHDK Forum
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raw average from a single raw picture?

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Offline Coutts

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raw average from a single raw picture?
« on: 01 / April / 2008, 14:08:24 »
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Alright i think the raw sum and average features are awesome, i just have a few questions.

Lets say i raw sum 10 60 second exposures together to make a 10 minute exposure in pitch black night at a corn field to get a star lit scene? Does raw sum also reduce noise as it averages the raws like raw average does?

Also lets say you need to use ultra high iso settings to get a quick shot handheld, instead of needing 10 different raws of the same thing, why not take 1 frame, and then duplicate that raw file 10 or 15 times and average the duplicates together? Wouldn't this give the same effect as taking 10-15 seperate shots?

BTW Raw Average works awesome! I took a picture at ISO 1600 and by averaging 20 exposures it eliminated all noise in the picture  :D
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Offline jetzt

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Re: raw average from a single raw picture?
« Reply #1 on: 01 / April / 2008, 14:54:13 »
Seems that I have to retry all the raw avarage, I only tested with 4 to 6 exposures and had far more noise.
So I can't help you ().

Does it also remove the pink area in top-left edge?

However keep on taking these great photos.
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Offline Coutts

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Re: raw average from a single raw picture?
« Reply #2 on: 01 / April / 2008, 14:59:08 »
after looking at it on my computer at full size it didnt get rid of 100% all of the noise but if you ask me its a pretty damn good quality picture for being at ISO 1600 (and we all know how bad the noise is on these cameras with anything above ISO 200)

Original ISO 1600 shot:


Processed raw from 25 frames at ISO 1600:
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Offline Coutts

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Re: raw average from a single raw picture?
« Reply #3 on: 01 / April / 2008, 15:00:24 »
this is with noise reduction on BTW.
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Offline PhyrePhoX

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Re: raw average from a single raw picture?
« Reply #4 on: 01 / April / 2008, 15:17:09 »
how long was shutter speed?
how hot got the camera? 25 raw sums, how long did it take?
btw i dont think duplicating one single raw 25 times and then averaging them to get rid of the noise is like pulling oneself out of the swamp using your own bootstraps. i'm almost 100% sure that it wont work.
will definitly test this raw sum & average more in future, seems really neat.
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Offline Coutts

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Re: raw average from a single raw picture?
« Reply #5 on: 01 / April / 2008, 15:21:17 »
exposure time was 1/320th of a second, iso 1600. I just held the trigger down in continuous mode for 25 pictures. didnt take long, mabe a minute or 2.
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Offline fbonomi

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Re: raw average from a single raw picture?
« Reply #6 on: 01 / April / 2008, 16:13:04 »
results are excellent!
so, yor finger was on the trigger for 1 minute?
or you have a very steady hand, or you have a very string tripod!

and yes, averaging 25 identical shots gives a result that is identical to the original!
just like the average of 123+123+123+123+123+123+123+123+123+123+123 .... still gives 123!
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Offline Coutts

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Re: raw average from a single raw picture?
« Reply #7 on: 01 / April / 2008, 16:34:22 »
Did some testing. Took 30 shots at ISO 2500 (maker notes recorded 2300). Exposure time was 1/30th of a second, room pretty dark. I compared processing the average from JPGs loaded into photomatix compared to RAWs processed by chdk on the camera. Heres the results:

Original:


30 Frames Averaged using Photomatix:


30 Frames Averaged in CHDK:


=D
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Offline Coutts

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Re: raw average from a single raw picture?
« Reply #8 on: 01 / April / 2008, 17:00:51 »
ok i confirmed it that it does not work to just duplicate the same picture and average it. i tried both JPGs and RAW files, both did not work. It just created a more noisy picture than what i started with so its a neg on doing that.

On a better note it looks like the raw average is pretty sweet and works awesome with alot of exposures.
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Offline Barney Fife

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Re: raw average from a single raw picture?
« Reply #9 on: 01 / April / 2008, 18:49:27 »
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« Last Edit: 22 / April / 2008, 15:45:51 by Barney Fife »
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