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Thread: Noise Reduction in Digital Camera RAW

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    Default Noise Reduction in Digital Camera RAW

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    I have been working with some images in Digital Camera RAW and noticed an interesting noise results when I am moving the sliders around for fill lighting. The image was metered from strong overcast backlighting and when I use a fair amount of fill lighting from the slider in the Digital Camera RAW in Adobe Bridge CS5 I get alot of noise showing up in the tan tones of a cedar waxwing - see original and adjusted copy attached in separate post. The interesting thing that happens when I start to slide the slider before I release it - the noise disappears an a more pleasing image results - until the slider is released.

    I am learning how to make better shots - so aside from starting from a better starting place (I will take advice there too!) I am curious how to better process my images to get the noise out when an image is not shot with the histogram enough to the right.

    Is this when I should get a CS Plug-In like Noise Ninja? Or can I solve this in Photoshop with better skills. Here is the adjusted image.
    Last edited by Cal Walters; 01-02-2011 at 01:32 PM.

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    Default Here is the original

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    Not sure of the best way to post the original to keep it under the 200 K file size so I took a screen shot and saved it in the dimensions as a JPEG - if there is a better way, please let me know.

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    Cal,

    When you move the sliders and observe the effect you describe, I assume you are not doing that at 100% view, correct? I think if you try it at 100% zoom, then as you move the sliders and it looks smooth, it should remain so after moving the slider.

    If you are at less than 100% zoom, then the slider action is only acting on the pixels on screen (to give faster response). When you lift off of the slider, the entire image is computed, and then sub-sampled again for the display. I think your experiment is showing a weakness in the sub-sampling algorithm. So try again at 100% zoom.

    Regarding the noise, one of the other tabs includes noise reduction. What you are seeing is chrominance noise and you should be able to reduce it on the noise reduction tab. I haven't used the chrominance noise tool much so I can't say how effective it is for your image.

    Roger

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    Roger,
    Thanks, I will give that a try. I'll try the 100% and see if I get the same impact.

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    Robert Amoruso
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    Cal,

    Your bigger problem here, based on the second scan is a very underexposed image - I say at least 2 stops. You need to be exposing to the right (Google "expose to the right" or "expose to right") and putting the highlights on the right side of the histogram.

    This pulls the shadows/dark tones up too in the histogram and reduces noise. The higher the signal creating digital data the less noise you will have. It is called Signal to Noise ratio.

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    Hi Cal,
    You are really pushing the software trying to get this to work. My understanding is that PS CS5 does bring in noise when you push the fill slider most of the way up.
    PS CS5 is also quite good at removing noise, so once you have moved the slider to the right, go to the sharpening and noise reduction panel and try increasing the noise reduction sliders. Definitely needs some chrominance noise reduction, probably needs luminance reduction too. I find that if I bring the detail slider for each in line with the noise reduction sliders it works well.

    In future if you are in a situation like this, as Robert suggested expose to the right (that is the right side of the histogram). But just in case you are not aware, that usually means adjusting your exposure compensation or EV. It is the +/_ button and the rear dial on Nikon DSLRS. I don't know about Canons but is should be similar. I hope this isn't too basic an answer and you already knew all about it.
    Take care,
    Clive
    PS. if you set the exposure compensation for a photograph don't forget to set it back to zero when you are done. ... we all forget this sometimes.
    Last edited by CliveTonge; 01-04-2011 at 01:54 PM.

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    Quote Originally Posted by Cal Walters View Post
    Not sure of the best way to post the original to keep it under the 200 K file size so I took a screen shot and saved it in the dimensions as a JPEG - if there is a better way, please let me know.
    Hi Cal. I have two comments that may help you here.

    First, Robert is correct in saying that the image appears under exposed. I suggest that before you do anything else, you should open your RAW file in PS CS5 Camera Raw, and then move the "Exposure" slider to the right without moving the histogram so far that it produces a spike at the right side. You will find that this will brighten your subject considerably. After that, you can make Fill Light and other adjustments as needed.

    That's the beauty of shooting in RAW, and making after-the-fact exposure corrections in Camera Raw.

    As for your concern regarding restricting file size, I adjust an image the way I like it as a Photoshop document, and then under the File drop down menu select "Save for Web & Devices..." After doing that, I enter the size limitations, keeping in mind the BPN 1024 pixel Width and 800 pixel Height limitations.

    Finally, to keep the file size down for posting, I go the the extreme upper right hand corner of the computer screen, I click on downward arrowhead to bring out the drop down menu, select "Optimize to File Size...", and set 190 as my limit. Then I click on Save, and name the image.

    I then sharpen my image if needed, and repeat the steps for saving for the web, again setting 190 as the limit in my optimization to file size.

    When you Save, you will be asked whether you wish to replace the prior unsharpened image, which you should do.

    Hope this helps. :)

    Norm
    Last edited by Norm Dulak; 01-04-2011 at 05:07 PM.

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    Thanks all, yes this is def under exposed. It was taken much earlier in my photo days (last year!) I've gotten much better since then, but the metering and lighting with bright overcast days like that one continue to flummox me a bit.

    Helpful points on both that and using exposure compensation before fill light and then dialing in the noise. On CS skills I am about where I was on photography last year.

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