Reduce Noise! New Way!

Discussion in 'Beyond the Basics' started by EchoingWhisper, Apr 1, 2012.

  1. EchoingWhisper

    EchoingWhisper TPF Noob!

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    I just thought of a new (maybe its old but it's new for me) way to reduce noise. Since noise is random, shooting more of the same shots would neutralise it. I think that if we stack the photos, we will get less noise. I'll try it out tomorrow.


     
  2. Mrgiggls

    Mrgiggls TPF Noob!

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    Think of noise as static on a TV channel that's not coming in very well (I'm talking about over the air broadcast that your grandparents watched). If you have a noisy image, merging more of the same is only going to give you merged noise. Noise reduction algorithms are designed to analyse the overal tone and luminosity of an area and take pixels and try to remove variances in that tone and luminosity and bring them down to a uniform and smooth level. This is why detail is lost. The pixels are changed to more closely match the neighboring pixels.

    I aplaud your spirit of ingenuity but I think if it were that easy, we'd have already been doing it for years.
     
  3. EchoingWhisper

    EchoingWhisper TPF Noob!

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    Guess it didn't work.
     
  4. Sw1tchFX

    Sw1tchFX TPF Noob!

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    It IS that easy, and people HAVE been doing it for years.

    If you're on a tripod, and you have 10 shots at ISO 1600, the random noise will blend together, however the detail (since it won't be moving) will still remain, because unlike random noise, it will be the only thing that will consistently be in the exact same place in each picture.

    I've done it with my D700, in camera with multiple exposure turned on, and it can make ISO 1600 look more like 200. It works, and works very, very well.
     
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  5. L4RRY

    L4RRY TPF Noob!

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    Im not sure but i think this is technology used in sony nex and sony alpha, they make 5 images and then reduce noise... Some people are using it manually (making few pictures and then combine them to have less noise) negative on this is that the images looses sharpness litle bit.
     
  6. Mrgiggls

    Mrgiggls TPF Noob!

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    Wow.....I stand corrected. I wasn't aware of image averaging, but a quick Google search shows it to be an effective and popular tool for astrophotography. Thanks Sw1thFX. Always a good day when you learn something new.

    My apologies Michael...I spoke before checking my facts.


    BTW...here is an interesting article I found on the subject.
     
    Last edited: Apr 1, 2012
  7. EchoingWhisper

    EchoingWhisper TPF Noob!

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    Lol I feel proud. I thought of this without ever reading anything similar. I just tried it and it works, my ISO 6400 looks clean. It's like shooting at a longer exposure with a lower ISO. One thing I couldn't get back though is the highlights.
     
  8. EchoingWhisper

    EchoingWhisper TPF Noob!

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    You don't actually lose sharpness. Noise increases the look of sharpness. Try increasing noise in Photoshop and you'll realise that the photos look sharper.
     
  9. JSER

    JSER TPF Noob!

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    Bit hard with windsurfing, motor cross, skateboarding etc etc
     
  10. Overread

    Overread has a hat around here somewhere Staff Member Supporting Member

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    Far as I know this is how most long exposure noise reduction programs work inside cameras. They take the same length of exposure with the shutter closed right after the first exposure and then remove the noise spots from the second shot from the first (since the second shot should only show black or noise image).

    Focus stacking in macro also makes use of this, whilst at the same time stacking the sharper parts of the shot together. And as said astro photography makes extensive use of this method (Esp if you don't have a liquid nitrogren setup to cool your camera for super long exposures).

    Also Echo - you needs get out and shoot more :)
     
  11. matthewo

    matthewo Been spending a lot of time on here!

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    Soo when would you actually use this much. If you take multipule images on a tripod at 1600 and merge them to get a noise reduction image similar to 200 iso. If your using a tripod on a still subject why wouldnt you just shoot at iso 100 and a longer shutter speed?
     
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  12. Alex_B

    Alex_B No longer a newbie, moving up!

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    This is in fact one standard way of noise reduction in scanners, just do a multiple pass scan and then average the final image.
     

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