# The Filter page

After you have created or loaded a noise profile, you can adjust the controls on the Filter page. The Filter page includes three groups of controls. The luminance group affects filtering of noise in the brightness component of an image. This is usually the part of the image that contains the most real information. The colors group controls filtering of color noise, which is often the most displeasing noise. The sharpness group enhances edge sharpness using an unsharp mask.

Strength controls how aggressively the filter is applied. This is the control that you'll normally want to adjust if you don't like what you see in the preview rectangle. If you move it far to the right, the image may look too plastic-like. If you move it to the left, it will look more grainy. Often the most natural-looking results are achieved when you leave a modest amount of grain. The human eye tolerates a certain amount of noise when it is accompanied by detail, and the luminance channel contains most of the detail in an image.

Smoothness increases or decreases the noise levels estimated by the Noise Profile. Usually the default setting is adequate, but if you see isolated specks in smooth areas, try increasing the smoothness setting to see if they go away. (Here's a tip for adjusting the Smoothness slider: Move the preview window to a smooth background areas, and move the Strength slider all the way to the right so the preview is a smooth as possible. Then set the Smoothness slider to the minimum level such that the preview is still smooth (if it is too low, you will usually see isolated specks). Finally, lower the Strength slider until you like the results.)

Contrast applies a scaling factor to edges, similar to an unsharp mask, but at several resolutions simultaneously. You probably won't need to adjust this in most situations.

Sharpness amount and sharpness radius apply a conventional unsharp mask to the filtered image. Some people prefer to set the amount to zero and do sharpening later in the workflow. However, even in that case, it can be useful to preview the sharpening effect to see how it interacts with the noise reduction.

In addition, there are some controls at the bottom of the panel. Filter coarse noise is occasionally useful when an image has very low-frequency noise, usually in the color channels. Turbo mode takes a few shortcuts to accelerate filtering. Usually the difference in quality is negligible, but strong diagonal edges might occasionally show some aliasing artifacts ("jaggies").

## A trick for adjusting the Filter controls

Here is a quick and easy strategy for adjusting the filter sliders that often yields excellent results:

1. Move the preview to an area that should be smooth.
2. Move the Luminance Strength slider all the way to the right.
3. Adjust the Luminance Smoothness slider to the lowest setting possible without introducing obvious speckling. The preview area should be smooth.
4. Now, reduce the Luminance Strength slider until you like the balance between detail and smoothness.

## Saving and reusing profile and filter settings

You can save the current profile and filter settings directly to a file by choosing the "Save" command in the Profiles menu. Use the "Open" command to load a saved settings file from disk.

## Selective filtering

You can use the Noise Brush to protect parts of the image from filtering.

You can also use selections in Photoshop to restrict filtering to a particular region. You can feather your selections in Photoshop for a gradual transition.

In addition, filtering is restricted to the layer and/or channel that you select in Photoshop before invoking Noise Ninja.