Pixiq

Noise in the digital era is the equivalent of film grain. The higher the ISO you use the more noise you’ll generate in your digital image. A few other factors can also greatly increase the amount of noise in an image such as underexposure (which in effect brings out more noise when you have to bring the exposure back up in the post-processing), the sensor size and resolution, long exposures and the amount of sharpening applied to an image. These factors all have an effect on how much noise is visible in any given image. Before we get into reducing noise, realize that noise isn’t necessarily a bad thing. It can give your image texture and a feel that you can’t get any other way. Sometimes you may even want to add noise for a certain effect (ala high speed film grain).

Another side note before we get into it here, with today’s amazing cameras like the Nikon D3s, D700 and Canon’s 1D Mark IV you may not need any noise reduction at all unless you are shooting at wildly high ISOs. With my D700 I am confident that the image quality is useable up to ISO 3200 and even 6400 with moderate amounts of noise reduction done after the fact. Sometimes I don’t even apply any noise reduction for images shot at these high ISOs depending on the scene and the effect I am going after. Yet another factor to keep in mind as we talk about reducing noise is that when you are looking at your image on the monitor at 100% you are seeing much more information than you will ever see in a print. To get a better idea of how the noise will look in print, adjust the noise while looking at the image at 100% (1:1) and then drop down to 50% (1:2) to approximate what it will look like in a print. Because of this you may not need to add as much noise reduction as you think.

For this blog post, I have chosen an image I shot at ISO 6400 (see above screenshot) while shooting an assignment with the Henry 1 Helicopter Search and Rescue unit out in Santa Rosa, California. I was using a tripod mounted 600mm f/4 lens about an hour after the sun had set and it was obviously quite dark. Hence, I had to crank the ISO way up to get anything useable.

Alright, let’s get into it here. In general there are two main types of noise in digital images: Chromatic or color noise (see image above) and Luminance or monochromatic noise (see image below). Color noise is easy to spot. If you have an image that seems to have red, green and blue dots or splotches all over the place this is easily recognized as Chromatic (color) noise. In contrast, monochromatic or Luminance noise is the stuff that looks like film grain – basically bunched up speckles. As you can see in the screenshots above and below, the image I have chosen to work on here has a bit of both types of noise.

The noise reduction controls in Lightroom are found in the Details dialog in the right panel of the Develop Module. The Detail dialog contains both Sharpening controls and Noise Reduction since they greatly affect each other. The noise reduction sliders translate as Luminance = monochromatic noise and Color = chromatic noise reduction.

If you ever used the noise reduction sliders in Version 1 or 2 of Lightroom, be aware that they have come a long way and are quite a bit better in Lightroom Version 3.x. I used to use Noise Ninja to reduce noise in images shot at high ISOs but now that Lightroom's noise reduction is so good and in fact on par with just about anything out there all I use is Lightroom.  But as I said above, these days it isn’t often that I even worry about noise with the new cameras. For images shot at ISO 1600 and below with my Nikon D700 I don’t even bother to correct noise because there is hardly any to worry about and certainly not any noise that will actually show up in a print.

To start with, it is best if you are zoomed into 1:1 (100%) on your image before you start manipulating the noise reduction sliders. This will allow you to see very clearly the effect each slider is having on your image. Since you have a preview window at the top of the dialog box you can also choose to have the main image window display your image at 1:2 (50%) or even larger than 1:1. Whatever your main image window displays the image preview at the top of the Detail dialog will always show you a section of your image at 100%. The defaults for noise reduction are 0 and 25 for the Luminance and Color sliders respectively. For images that don’t need any noise reduction I find these defaults to be just fine. Unlike the sharpening sliders, which always have the same defaults but are tuned specifically for each camera on the back end, the noise reduction sliders are not specific to a certain camera. I just wanted to make you are aware of that since the default settings may look just fine for my low ISO images, but they may not be all that great for your camera if you shoot something other than a Nikon D300, D700 or D3.

Another side note here, I have found that working on an original RAW file or a 16-bit Tiff file yields the best results. If you are working on jpegs I would save them as Tiff files first so repeatedly saving the file doesn’t destroy image data. Better yet, if you normally shoot jpegs instead of RAW, I would test your camera’s noise reduction settings for high ISOs and use the in-camera noise reduction as that might yield better results for jpegs specifically.

Ok, back to the grind here. Now that we are at 100% (1:1) on our image, I would start with the Color noise reduction and move the slider back and forth to get an idea of what effect it has on your image. If you didn’t see any color noise in your image this slider will have little effect. The good news about the Color slider is that it does not really affect image sharpness or detail too much. But just in case you have an image where it is you can pull the Detail slider just below the Color slider to the right and this will bring back as some of the detail. Hence, you are only looking to remove the red, green and blue color splotches. In the screenshot above you can see a before and after example of using the color noise reduction.

Once you have removed any color noise, it is time to move on to the Luminance slider. Before you get too heavy handed with the Luminance slider, realize that the more you move the slider to the right, the more image detail you are losing. This slider is basically applying a fancy gaussian blur to your image, in effect smudging the details to remove the noise. This slider is definitely applied to taste, but I would encourage erring on the side of less Luminance than more and remembering that a lot of the noise won’t be visible in the final print. And just as with the Color slider, we have detail slider and additionally a contrast slider here just under the Luminance to help bring back some of the detail and contrast in the image if need be.

As you can see, Lightroom’s noise reduction tools are quite simple. By adjusting the two main sliders you can get a feel for just how much noise can be removed. I would also suggest that if you crank the Luminance slider over to the right, that you add a little more sharpening back into the image. This will make it look snappy and keep you from losing too much image detail.

That is pretty much it for the Lightroom noise reduction controls. I have found that for images that just need a touch of noise reduction the Lightroom controls work quite well. I would say experiment with this tool on your own and print a series of images on your ink jet printer to get a feel for how much sharpening is too much. And just in case you were thinking wow, there is still a lot of noise in that image – well there is, but it was recently reproduced in my  book on adventure sports photography Digital Masters: Adventure Photography as a double page spread 18-inches wide and it looks stunning.

................................

If you are interested in developing a complete workflow of your own using Lightroom and perfecting your color management, I would recommend checking out my Lightroom Workflow e-book Adobe Photoshop Lightroom: A Professional Photographers Workflow. You can purchase that eBook for the low price of 24.95 on my website.

This e-book presents a complete workflow which includes my in-camera settings, how to determining the optimum white balance and exposure, color management, working with Lightroom and Photoshop, creating web galleries, Noise Ninja and much, much more. A sample table of contents is available for download on my website if you want to see exactly what is covered. The e-books is also up to date and covers the latest versions of Lightroom and Photoshop.