7.3. Edge
| 7. Edge-Detect Filters |

### 7.3. Edge

#### 7.3.1. Overview

Figure 16.138. Applying example for the Edge filter

Original image

After applying the filter (Sobel option)

Figure 16.139. Applying examples for the Edge filter

After applying the filter (Prewitt option)

After applying the filter (Gradient option)

Figure 16.140. Applying example for the Edge filter

After applying the filter (Roberts option)

Figure 16.141. Applying example for the Edge filter

After applying the filter (Laplace option)

#### 7.3.2. Activating the filter

You can find this filter through Filters → Edge detect → Edge....

#### 7.3.3. Options

Figure 16.142. Edge filter options

Algorithm

  Edge detector offers several detection methods:

  - Sobel: Here, this method has no options and so is less interesting than the specific Sobel.

  - Prewitt: Result doesn't look different from Sobel.

  - Gradient: Edges are thinner, less contrasted and more blurred than Sobel.

  - Roberts: No evident difference from Sobel.

  - Differential: Edges less bright.

  - Laplace: Less interesting than the specific one.

Amount

  A low value results in black, high-contrasted image with thin edges. A high value results in thick edges with low contrast and many colors in dark areas.

Wrap, Smear, Black

  Where the edge detector will get adjoining pixels for its calculations when it is working on the image boundaries. This option will only have an effect on the boundaries of the result (if any). Smear is the default and the best choice.

7.2. Difference of Gaussians |  | 7.4. Laplace