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Noise reduction techniques

Discussion in 'Image Processing' started by Zancrow, Feb 3, 2016.

  1. Zancrow

    Zancrow Mu-43 Regular

    152
    Jul 16, 2014
    Hello, I was wondering how you guys go about reducing noise while keeping detail and sharpness in your photos. I been trying Lightroom's noise reduction but I'm not too happy with it or maybe I'm doing something wrong. I have access to Lightroom 4 and Photoshop cs6.

    Thanks you.
     
  2. GBarrington

    GBarrington Mu-43 Veteran

    Here's a quick and easy NR technique I figured out when doing some testing on ACDSee Pro regarding Noise reduction. I haven't tested it with Lightroom, but I should think it will work with any product that can quickly desaturate/resaturate an image and which has separate sliders for chroma and luminance noise. I should think any product with a raw development module would have this. It would not work with more primitive single "noise" sliders.

    Glen Barrington - My Dynamic Range: A Quick and Easy NR Technique

    While I still have and use Topaz Denoise for problem photos heavy with noise, I find that ACDSee is now quite useful for noise control for Oly m43s photos up to, say, ISO 1600 or so.
     
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  3. David A

    David A Mu-43 All-Pro

    Sep 30, 2011
    Brisbane, Australia
    You have to know what the different sliders in LR accomplish in order to get the best results.

    Sharpening affects noise so you need to consider sharpening first. You can increase or decrease the visibility of noise in the image by your sharpening choices. Get them right first.

    Amount does what it says, increases or decreases the amount of sharpening.

    Radius controls how many pixels the sharpening effect is to extend on either side of an edge. If you have an image with lots of edges like leaves on trees, or thread detail in fabric which are placed close together and you want to make them distinct, you want to reduce the radius. The radius setting of 0.8 in the Sharpening-Scenic preset is a good choice. If you have an image of a face and you don't want to make every pore and skin feature appear distinct you want to increase the radius. The preset for sharpening faces uses a radius of 1.4 which is also a good choice for a starting point.

    Detail controls the sharpening algorithm used. A low setting acts to minimise halos, a high setting uses a deconvolution algorithm. In between they get blended in different degrees. I don't really understand what the terms mean but if you have an image with a lot of noise, setting Detail too high can actually sharpen the noise and make it more obvious so on really noisy images try reducing the Detail setting.

    Masking sets a threshold for what will and will not be sharpened. Hold down the Option key and the image becomes monochrome and some of the image will be black, some white. White areas get sharpened, black areas don't. Moving the slider to the right increases the black areas and limits the areas of the image being sharpened. Some masking is usually beneficial but how much depends on the image.

    Do your sharpening with the image zoomed in to 1:1 so you can see the effect of the changes. You can't really judge what you're doing if you're not at 1:1. My only exception to that is with Masking and I often go back to a full view of the image after setting Masking and hold down the Option key in order to see how much of the full image is being masked. When it comes to using the Amount setting what I tend to do at a 1:1 zoom setting is to increase the amount gradually until I start to see a grainy effect in the smaller preview window in the Detail panel on the side. I leave that preview window set to a 2:1 zoom so I can see 1:1 in the main image area and a 2:1 zoom in the small preview window. Once I start to see that grain effect, which is noise getting worse, in the preview window I back off the Amount slider a bit until it becomes less objectionable.

    Once you get the sharpening done, then start on the noise reduction. There's 2 sorts of noise, luminance noise and colour noise. The Luminance slider controls luminance noise but increasing the amount of noise reduction too far will actually end up reducing sharpness. Adobe say that a setting of 25 provides a good balance between noise reduction and sharpness and I try not to go beyond that if possible. If you start having to go really high with the Luminance slider, you may need to go back and play with the sharpening sliders a bit in order to correct any loss of sharpness the noise reduction has introduced. Basically it's a bit of a juggling act between sharpening and noise reduction to get the best result. The Color slider controls colour noise reduction. For most of my images I only ever adjust the Luminance slider, occasionally the Color slider, and I tend to leave the other sliders at their default settings.


    Noise tends to be worse in the shadows and you can apply both noise reduction and sharpening in local areas of the image with an adjustment brush or graduated or radial filter. Adjust your settings to suit the bulk of the areas in the image and then use a local adjustment to modify those settings in the other areas. All you can do with a local adjustment is to increase or decrease the amount of sharpening and noise reduction applied, you can't change the other settings. With Sharpening, a setting of -50 in a local adjustment will eliminate all sharpening, higher settings start to increase a gradual blur which can be handy if you want to reduce the visibility of skin features in a portrait or something like that.

    If I have an image with shallow depth of field, so not too many really sharp areas, or shadow areas in which fine detail isn't clear so something like a night time available light shot and I'm trying to keep the shadow areas in shadow in my processing, I find I get better results with both noise and apparent sharpness by increasing the Radius above 1.4 and decreasing the sharpening Detail setting to 25 or less. plus increasing Masking. That tends to reduce the visibility of noise in the image quite a bit and means I need lower noise reduction settings.

    It takes a bit of practice using the sliders and seeing what they do to get the hang of it but once you get the hang of it you may be surprised at the difference in your results with Lightroom.
     
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  4. Understanding how to use sharpening and masking together is probably the most important thing.
     
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  5. Turbofrog

    Turbofrog Mu-43 Hall of Famer

    Mar 21, 2014
    One technique that can often be helpful is to reduce your sharpening on the overall image to 0 and then add sharpening selectively with the brush tool to in-focus areas, texture-rich areas, and detail areas. This will make out-of-focus areas much creamier, and minimize the appearance of noise substantially. I think that the default 25 sharpening that Lightroom has influences the perception of how noisy M4/3 files are, it makes a big difference.

    Here's a 100% crop of an image at ISO 1000. Not high, but cleaner than people might expect out of M4/3. That sharpening noise is now only visible in the shadowy underbelly.

    SosLZUY.
     
    Last edited: Feb 3, 2016
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  6. David A

    David A Mu-43 All-Pro

    Sep 30, 2011
    Brisbane, Australia
    That's the approach I was referring to when I suggested using local adjustments. That end result can be obtained in 2 ways:

    - Zero sharpening on the whole image and brush the sharpening in where you want it as Turbofrog suggests. If you want to do that, it can be hard to judge the effect of the other settings as you make them. It's better to make your sharpening settings including Amount first then just reduce the amount to Zero to eliminate sharpening. Then you apply the brush and set the sharpening Amount to the setting it was before you zeroed it. That way you can judge your settings better while you're making them.

    - The alternative is to sharpen the whole image based on how you want it your subject sharpened and then to use a brush or filter to reduce or remove the sharpening everywhere other than the subject. As I said above, a Sharpening setting of -50 in a brush or filter will eliminate the sharpening from the areas covered by the brush or filter.

    It's the same end outcome either way and the only real difference is in the amount of work involved in brushing sharpening into the subject or out of the other areas. When making local adjustments with brushes or filters I often make choices like that on how easy the work is going to be. I often choose the approach which needs less work but not always. If there's a really large area of brush work involved which is often the case when you're brushing something out, it's often easier to use a graduated or radial filter and then use the brush option in the filter to adjust the mask for the filter to cover the areas you want to affect. The OP won't be able to work that way in LR4 because brushes in filters were added later. I know it's in LR6 but I think it may have been added in LR5. It was not in LR4. I actually think the ability to modify a graduated or radial filter with a brush is pretty much enough reason to upgrade from LR4. I find it an extremely useful feature.
     
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  7. David A

    David A Mu-43 All-Pro

    Sep 30, 2011
    Brisbane, Australia
    Addition to my last post on brushing in or brushing out sharpness:

    If you're going to be making other local adjustments, so there are other ways besides sharpness in which the subject is going to differ from the rest of the image, pick the option that works best with making the other adjustments in the same brush or filter. It's better to change 3 different things for the same area with one brush or filter than to change them with 3 different brushes or filters covering the same area, and it's less work.

    If you want no sharpness in the background and you want it more "soft focus" than it is, use a brush or filter to remove it from the background and either use a sharpness setting closer to -100 than just the -50 needed to eliminate sharpening because that will introduce a bit of blurring, or use a negative clarity adjustment, or a bit of both.

    If you're brushing sharpness in, you can also brush in a little extra noise reduction if necessary but you'll have to juggle the amounts of sharpening and noise reduction because brushing in increased noise reduction will reduce sharpness.
     
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  8. Zancrow

    Zancrow Mu-43 Regular

    152
    Jul 16, 2014
    Thank you guys, this really helps! I will give these a try. :2thumbs:
     
  9. GBarrington

    GBarrington Mu-43 Veteran

    One other thing, I'm finding that noise isn't always a bad thing as a graphic element. Take Turbofrog's bird photo above, for instance. As he correctly points out, some visible noise remains in the bird's underbelly, but I think it adds some very subtle, but interesting texture to the image. I don't think the photo would have been as strong if the same level of Noise control had been applied there as it had elsewhere.

    I also like a hint of noise in sky and big blurry patches of background. It adds texture in what can be a boring nothingness. I admit though, it's a delicate balance and you aren't going to please everyone with your choices.
     
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  10. Zancrow

    Zancrow Mu-43 Regular

    152
    Jul 16, 2014
    Agreed, GBarrington. I like the texture noise gives in some black and white photos, very film like.
     
  11. mcasan

    mcasan Mu-43 All-Pro

    Feb 26, 2014
    Atlanta
    Macphun's Noiseless is excellent. I never need more that the lower two strengths. And you can dial in how much micro contrast and structure you want added. It is way beyond LR capabilities.
     
  12. Drdul

    Drdul Mu-43 Regular

    104
    May 16, 2015
    Vancouver, BC
    Richard
    I was struggling in Lightroom to get a good result with several high-ISO images from my E-PL5 (and by high-ISO I mean 2500+). No matter what I did with the noise reduction settings (and sharpening settings) the image would look "crunchy" at 100%. So I took an image and ran it through Imagenomic's Noiseware, and got much better results. Then I tried another, and another. I prefer to use Lightroom as much as possible, but when it can't deal with the noise, I use Noiseware instead. FWIW, I own and have tested several other noise reduction plugins, and I like Noiseware the best.
     
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  13. mcasan

    mcasan Mu-43 All-Pro

    Feb 26, 2014
    Atlanta
  14. David A

    David A Mu-43 All-Pro

    Sep 30, 2011
    Brisbane, Australia
    I'm not certain what you're asking here.

    There is only 1 slider for sharpening in the adjustment brush, graduated filter, and radial filter panels, and only 1 slider for noise reduction in those panels. Those 2 sliders adjust the amount of sharpening or noise reduction applied. You can only adjust the amount of sharpening and/or noise reduction in these local adjustments. You cannot change other settings like the Radius, Detail, and Masking settings for Sharpening.

    So, for both Sharpening and Noise Reduction you need to set the parameters to be applied to the whole image in the Detail panel. You can adjust the amount of each to be applied in localised areas of the image with the brush or filter.

    There is one difference between the Sharpening and Noise Reduction sliders in the local adjustments. Positive adjustments for both work like positive adjustments in the Detail panel so if you have an amount of +10 in the Detail panel and you brush in an adjustment of +5 in an area, the result in that area should be the same as it would have been in that area if you had used +15 in the Detail panel. Negative adjustments work differently.

    For Sharpening in the local adjustments, a setting of -50 eliminates all sharpening in the area covered by the local adjustment, so a local adjustment of -50 Sharpening is equivalent to setting the Sharpening amount to 0 in the Detail panel. Sharpening adjustments of -51 to -100 introduce increasing amounts of blur. The slider for Noise Reduction in the local adjustment panels just reduces noise reduction on the same basis as the slider for Amount in the Detail panel increases it.


    If you want to use 2 or more different "types" of sharpening in an image, e.g. a radius of 1.4 and a detail setting of 25 in one area and a radius of 0.8 and a detail setting of 60 in the rest of the image, you cannot do this in Lightroom. You have to use Photoshop and layers in order to achieve that sort of result. I know it can be done, I have read instructions on how to do it, but I do not have Photoshop and I have no experience of using Photoshop so I can't help any further if that's what you want to do.

    LR only allows one set of parameters for Sharpening and one set for Noise Reduction in an image but it does let you vary the amount of sharpening and noise reduction applied in different parts of the image.
     
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  15. Frankgr

    Frankgr Mu-43 Regular

    43
    Oct 18, 2014
    Thank you for this. I will print it out and experiment