| iTool User's Guide: Working with Images |

## Filtering an Image

There are six types of filters available in the iImage tool.

### Convolving an Image

To convolve an image:

1. Select the image to be convolved.

2. Select Operations Filter Convolution.

3. The convolution filter editor appears and desired settings can be edited.

4. Click OK and the filter is applied.

For more details on the convolution filter, see Convolution Filter.

### Applying a Median Filter

The median filter replaces each pixel with the median (a value in an ordered set of values with an equal number of values above and below it) of the two-dimensional neighborhood of a given width.

To apply the median filter to an image:

1. Select the image.

2. Select Operations Filter Median.

For more details on the median filter, see Median Filter.

### Smoothing an Image

The smooth filter removes unwanted noise from an image using a weighted average.

To apply the smooth filter to an image:

1. Select the image.

2. Select Operations Filter Smooth.

For more details on the smooth filter, seeSmooth Filter.

### Applying a Roberts Filter

The Roberts filter uses the Roberts edge enhancement operator to detect edges within the image.

To apply the Roberts filter to an image:

1. Select the image.

2. Select Operations Filter Roberts.

3. The Roberts filter is applied.

### Applying a Sobel Filter

The Sobel filter uses the Sobel edge enhancement operator to detect edges within the image.

To apply the Sobel filter to an image:

1. Select the image.

2. Select Operations Filter Sobel.

3. The Sobel filter is applied.

### Applying an Unsharp Mask

The unsharp mask enhances the contrast between neighboring pixels in an image.

To apply the Unsharp Mask filter:

1. Select the data that you want to unsharp mask.

2. Select Operations Filter Unsharp Mask.

For more details on the unsharp mask filter, see Unsharp Mask Filter.

IDL Online Help (March 01, 2006)