There are several different ways to reduce noise in an image.

• Photoshop's Despeckle Command

• Photoshop's Reduce Noise Filter

• Commercial third party plug-ins and stand-alone programs such as Noise Ninja, Neat Image, Noiseware, Topaz Denoise, and Niks Define.

The Despeckle Command

• Go to Filter > Noise > Despeckle.

• Repeat if necessary.

Figure 1 - Noise reduction using Photoshop's Despeckle command. Hold your mouse cursor over the image to see a comparison between the original image and the noise-reduced one.

The only problem with Despeckle is that you don't really have any control over it except by using the Fade command (Edit > Fade Despeckle). Still, it works pretty well with planetary images and is easy to use.

The Reduce Noise Filter

The Reduce Noise filter gives much more control over the amount of noise reduction and how it is applied.

• Go to Filter > Noise > Reduce Noise. The Reduce Noise filter dialog box will open (Figure 3).

Figure 3 - Photoshop's Reduce Noise Filter

• Go to Filter > Noise > Reduce Noise. The Reduce Noise filter dialog box will open (Figure 3).

• Adjust the Strength slider (Figure 2, Number 1).

• Adjust the Preserve Details slider.(Figure 2, Number 2).

• Adjust the Reduce Color Noise slider (Figure 2, Number 3).

• Adjust the Sharpen Details slider (Figure 2, Number 4).

• You can also go into the advanced settings in the Reduce Noise Filter dialog box and apply noise reduction to each channel individually.

Figure 4 - Jupiter with the noise reduced with Photoshop's Reduce Noise Filter. Hold your mouse cursor over the image to see a comparison between the original uncorrected image and the corrected one.

In Figure 4 we can see the results of using Photoshop's Reduce Noise Filter to reduce the noise in the image.

Both the Despeckle command and the Reduce Noise Filter work well to reduce noise in planetary images.

Note that it is possible with some noise-reduction techniques to reduce the noise so much the image looks plastic and unrealistic. Don't overdo noise reduction. The human visual system expects to see a little bit of noise in an image.