Noise Control

Let’s talk noise control!

While my stance on high ISO noise has loosened up somewhat since I began using strobes at wedding receptions, it’s still somewhat of a concern. Generally speaking, ISO3200 on the 5DMKII still looks pretty darn good and we’ve come a long way as far as high ISO noise handling is concerned. But it still always helps to have a good NR workflow in place.

So I’d like to discuss how I typically handle noise.

Prerequisites:

  • Adobe Camera Raw 6.x
  • Photoshop CS5
  • NR Plugin such as Neat Image Pro or Noise Ninja

You don’t need these exact items. As long as you are able to follow along, conceptually things should be the same regardless of the software used.

It’s common to see folks apply noise reduction via a NR plugin in one fell swoop and while this may work for less noisy images using the supplied profiles for your specific camera, it’s not the most ideal way to reduce noise. Think about it. Where do you notice noise the most? I would say in shadow areas, especially areas where there are little to no details. You notice it a lot less in the highlight areas, areas of detail, and even very dark areas. So knowing that, why would you apply the same amount of NR in shadow and highlight areas? That doesn’t make any sense and what you end up with is too much NR applied that sometimes results in that dreaded “pastel” look.

For me, the goal is not to completely get rid of all noise, but just enough that it’s not a problem. Leaving a little grain behind is perfectly acceptable for most situations. You always need to consider the end product. Web? Album? Small print? Large print? The necessity for a good NR workflow will vary based on that.

Anyways, let me now demonstrate my NR workflow!

Firstly, let’s set the scene. Here’s the target photo:

(5DMKII + 50L at f1.2, 1/125, ISO3200. Didn’t need to adjust exposure, so it’s representative of a typical ISO3200 file from the 5DMKII.)

Jessica and Michael Wedding

Below is a composite image of 100% crops taken from different areas of the photo.  Notice that there are different levels of apparent noise. based on where the crop was taken from. The left section is taken from the darkest part of the photo. It’s certainly grainy but the color noise isn’t that bad. The middle section is taken from the main subject. Again, the noise isn’t all that bad. You can see a lot more noise on the right section. This section is more in-between and is an OOF area of the image which seems to make noise more apparent. This is straight out of the camera, with no NR applied. This means the NR controls in ACR were explicitly zeroed out. So you are seeing color and luminance noise at its fullest.

OK, so let’s apply some NR on the photo using Neat Image Pro in full automatic mode and see what it looks like.

You can see how it cleaned up the grain nicely but it also killed some of the details, especially on the face. I don’t think it looks all that terrible actually, but let’s see if we can try something different.

So let’s try to apply NR in multiple passes.

The first step is to reduce color noise from the entire photo. ACR actually does a very good job doing this. I usually set color noise reduction to 25 and leave the rest to 0. Here’s the result.

Again, you can see that it did a very good job. In fact, I’d say this is good enough for typical usage. But let’s see if we can reduce the grain a little bit.

In Photoshop CS5, select the shadow areas via Select->Color Range. Select “Shadows” from the drop down list as shown below.

Here’s the image with the shadows selected.

Then open your favorite NR plugin. For this example, we will use Neat Image Pro. We are SELECTIVELY applying NR and since we are applying NR on the shadow areas, we will be a little aggressive with the settings. However, again, the goal is to reduce grain, not to eliminate it.

Here’s the result. You can see that it’s a very subtle change and the face remains untouched due to the selective NR. You can tweak the settings and be more aggressive with the NR if that will suit your needs. Personally, I like it more subtle like this.

Now let’s apply NR on the highlights. All you have to do is inverse the selection via Select->Inverse. Now you have the highlights selected.

Once again, go into your favorite NR plugin and apply NR. But this time, pull back on the settings a little bit since we don’t need to apply as much.

Now let’s check out the result. You can see that we’ve reduced some grain on the face but retained some details as well. The left section and right section were not touched of course because we did an inverse on the selection.

Again, I think it’s a very subtle difference. The difference might be more noticeable on higher ISO images or if you are more aggressive with the settings. But I think it looks more natural than the automatic NR that we applied earlier.

Here’s the finished product. Of course you can’t really see anything with web-sized images, but you get the point.

Jessica and Michael Wedding

I have all the steps in an an easy to use action so it’s never a hassle to apply NR this way.

Hope this comes in handy for some of you! 🙂

 

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