Noise Reduction

Discussion in 'Graphics Programs and Photo Gallery' started by bogleric, Nov 11, 2006.

  1. bogleric

    bogleric TPF Noob!

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    I took this photo at iso 800 with the total intent of trying to improve my noise reduction skills. I use photoshop CS2 with noise ninja, and when i get the noise out the image is too blurry. I apply an unsharp mask and it just doesn't come out right.

    here is an un-edited image..... thoughts/suggestions?

    [​IMG]
     
  2. Tiberius

    Tiberius TPF Noob!

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    No way around it. Noise Reduction reduces sharpness. After that all you can do is tweak with various sharpening tools (like the Unsharp Mask) to get the result you desire. Personally, I find that all the modern DSLRs are quite acceptable at High ISOs, and I'd rather have a noisy sharp image than a smooth blurry one.
     
  3. JonK

    JonK I want MORE!!

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    I took a close look at this image and, honestly, I dont find it all that noisy. I'd leave it as is.
    And I agree with tiberius...no way around it, noise reduction also reduces sharpness. Only thing to do is go easy with the noise reduction and only use it when necessary.
     
  4. David

    David TPF Noob!

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    Whilst I agree there will always be some loss of sharpness, it is possible to reduce this to negligible amounts. I have developed a technique and action for reducing noise with PS CS2, that pretty much retains all the sharpness in an image. It has allowed me to use the reduce noise filter at near maximum strength, with next to no loss of edge detail.

    It works by using the find edge filter to create a mask via an alpha channel, which when applied to the image, allows the sharp edge detail to be retained after using the reduce noise filter. I posted it in another thread a short while ago, which includes both the method and a link to download the action, and it can be found here (mine's the fourth post in the thread). ;) As the post says, there are some 'stops' in the action to explain what is going on, but feel free to remove these, or amend the action as required. It stacks up quite well against some of the plug-ins you can buy. In the linked thread is an image that it has been applied to. Hope it helps.

    David
     
  5. Big Mike

    Big Mike I am Big, I am Mike Staff Member Supporting Member

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    Thanks David...I'm going to give that a try.

    Something I have been wanting to try...is run noise reduction and layer it over the original image...then just use a layer mask to pain back in the sharpness, where I think it is needed. Or do it in the opposite order...and paint the mask over the noisy parts.
     
  6. David

    David TPF Noob!

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    Cheers Mike. Creating a mask using the find edge filter allows the sharpness of the original image to show through the copied image on which you've reduced the noise. You shouldn't find yourself with too much of an edge, but you can always run a gaussian blur on the alpha channel before applying it as a mask. You can also do some painting on the mask layer if any area such as small writing, is missed by the find edge filter.

    As an aside, you can also use this technique in reverse to sharpen an image without introducing noise to large flat areas. I use this technique most on close up images of aircraft and cars, and it works wonders on those shots of brides getting out of their wedding car. A tiny bit of extra sharpness to bring out the detail of the dress and flowers, without introducing any noise to the metalwork of the car.

    David ;)
     
  7. Big Mike

    Big Mike I am Big, I am Mike Staff Member Supporting Member

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    Now that I look back at the earlier post...is says you developed it for CS2...which would explain why it didn't work for me on CS.

    So I changed the noise reduction to noise/median and it seemed to work well enough.

    The overall technique is still a little past my level of understanding...but I'll definitely look into it further.
     

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