Adobe Photoshop CS5 for Photographers - Martin Evening [129]
In Photoshop itself there is the Reduce Noise filter, which can also do a fairly good job of removing noise, except you can only apply the filter to one image at a time. You could always create an action and apply this as a batch process to a group of images, but this can still be quite a costly exercise in terms of the time it would take to process a group of images. I think the main reason why the Reduce Noise filter still has value (as well as the third- party solutions mentioned below) is that you can use it to process scanned film images directly in Photoshop.
Third-party noise reduction
If you are dissatisfied with the results from Photoshop's Reduce Noise filter, there are third-party noise reduction programs you can buy such as Noise Ninja™ from Picturecode, Neat Image™ or Noiseware™ from Imagenomic. These are just two of the more popular products favored by photographers. Noise Ninja is held in high esteem, but I am personally more familiar with Noiseware and have certainly been impressed by the way it is capable of removing noise from even the most tricky subjects, particularly grainy film scans. Noiseware offers a number of preset settings that can be applied to various types of film scanned sources and manages to do a good job of counterbalancing the need to remove noise while retaining edge sharpness in an image. Both of these are good products, but I would now maintain that the new improved noise reduction capability that's built into Camera Raw may change people's mind as to whether these plug-ins are needed still.
Reduce Noise filter
The Reduce Noise filter can be found in the Filter Noise menu in Photoshop (Figure 4.16). This filter uses a method of smart noise reduction that is able to remove noise from an image, but without destroying the edge detail in the picture. Overall, the Reduce Noise filter is most useful at reducing the noise from digital capture images. It is less good at reducing the film grain noise that's found in scanned film images. This filter is mainly designed to target the two main problems found in digital images, which are luminance and color noise. Luminance noise is like a very fine speckly grain, while color noise commonly occurs in digital captures that have been shot at high ISO settings. The only problem with this filter is that it is quite memory intensive, so you'll have to be prepared to wait a little while it performs its calculations.
Figure 4.16 Here is the Reduce Noise filter being used to help remove the noise from a digital capture which was shot at 3200 ISO; the Reduce Noise filter helped get rid of most of the noise artifacts.
In Basic mode you can simply adjust the strength of the noise reduction and then adjust the controls below (in the order they are displayed) to modify the noise filtering. The Strength slider adjusts the amount of noise reduction that is applied, while the Preserve Details slider helps preserve the edge luminance information. The luminance noise reduction appears strongest when you set Preserve Details to zero %, but as you increase Preserve Details, more edge detail (and often more noise) will become visible. The one thing you have to watch out for is that when you apply extreme settings you can sometimes end up enhancing the underlying noise patterns. Below that is the Reduce Color Noise slider. This allows you to control the color noise suppression and can be quite effective at removing heavy noise. There are times when you may want to crank up the Reduce Color Noise to 100%, in order to remove as much of the noise artifacts as possible, but be aware that adding too much color noise reduction can sometimes cause colors to bleed