Before you want to remove noise in a Photoshop image, it's best to check the channels in the Channels palette.
If you work in RGB (most of us do) then you can click on each of the 3 channels to get an idea of how much noise it contains. In this screenshot the Green channel was checked:

 

Images shot by digital cameras can often have a lot of noise in the blue channel. What people normally do in such a case is slightly blurring the blue channel.

But the problem with our image is more severe. Have a look at the following image:

 

In the upper left corner you can see a zoomed section of the water, sky and rocks. Notice that there is a lot of visible noise.
When we check all 3 channels ( red, green and blue) then we notice that there is actually a lot of noise in every channel.
Slightly blurring each channel wouldn't solve our problem in this specific image, it would blur the image too much.

So how are going to solve this? Let me say that it's not easy with any version of Photoshop that was released before Photoshop CS2, simply because none of the older versions have a descent noise removal filter. Now I can suggest you all kind of techniques that might be helpful if you use any of these older versions, but I'm going to be honest with you; the results are not going to look good.

The only good alternative for owners of older versions of Photoshop is to acquire a special noise removal plug-in.
There is one that I can strongly recommend:

• Neat Image

I advice this software because I consider it the best noise removal product in the market (and I've tested a lot of them). Why is this plug-is so good? It's because it actually analyzes the noise inside the image and uses special algorithms to remove it with sometimes mind boggling results.
You can read more about in our review of this product: Neat Image review

I've tested the new Reduce Noise filter in Photoshop CS2 and although it delivers much better results than any older Photoshop version can offer, it still has a long way to go to be as good as Neat Image or Noise Ninja.
So if you think about buying any of the two plug-ins, then you can be sure that you're absolutely not wasting your money even if you decide later to buy Photoshop CS2.

So in this section I'm going to show you how to remove noise inPhotoshop CS2 only. Does that mean that if you don't own Photoshop CS2 that you should skip this step? No, the techniques that I will be showing are also useful in older versions of Photoshop and that's because I avoid to remove noise in very detailed areas like the rocks for example, except for its dark shadows.

Ok, let's start.

In this image I will not remove the noise in the complete image. There are three reasons for that:

• The most visible noise is mostly in the water, shadows and sky
• Removing the noise in the detailed rocks would make them look slightly blurry and I want to avoid that
• By avoiding blurring the fine details in the rocks, the rock will be the sharpest part in the image, they will stand out and give the image slightly more depth (we're faking depth by trying to imitate a camera).

Make the Background layer the active layer by clicking on its thumbnail, which will then have a double border.
Click on the Background layer's thumbnail and drag and drop it onto the Create a new layer icon :

Double click on the name of this new layer and it rename it to Sky Noise.

 

Hold down the Alt key (Option key on the Mac) and drag and drop the Blue Sky layer mask onto the Sky noise layer:

 

Click on the thumbnail of the Sky Noise layer to make sure that its mask is not selected:

 

Go to the menu and select Filter / Noise / Reduce Noise... and use the following settings and click OK:

Make the Background layer the active layer by clicking on its thumbnail, which will then have a double border.
Click on the Background layer's thumbnail and drag and drop it onto the Create a new layer icon :

Double click on the name of this new layer and it rename it to Water Noise.

 

Hold down the Alt key (Option key on the Mac) and drag and drop the Water layer mask onto the Water Noise layer:

 

Click on the thumbnail of the Water Noise layer to make sure that its mask is not selected:

 

Go to the menu and select Filter / Noise / Reduce Noise... and use the following settings (same as we used for our sky) and click OK:

Make the Background layer the active layer by clicking on its thumbnail, which will then have a double border.
Click on the Background layer's thumbnail and drag and drop it onto the Create a new layer icon :

Double click on the name of this new layer and it rename it to Shadow Noise.

Select the Magic Wand tool in the tool bar.
Check the options bar and make sure that all the settings are the same as in this screenshot:

Move your mouse cursor to this dark area of the image and click ...

...which will select the darkest areas of your image:

 

With the Shadow Noise layer still active, click on the Add layer mask icon to create a mask from this selection and then click on the thumbnail of this layer (marked with red) to make sure that its mask is not selected:

 

Go to the menu and select Filter / Noise / Reduce Noise... and use the following settings and click OK:

Note: you're always free to use third party plug-ins that were specifically develop for noise removal. A good product is Neat Image which we reviewed on our site on this page.