8.3. Edge

8.3.1. Overview

Figure 17.139. Applying example for the Edge filter

Applying example for the Edge filter

Original image

Applying example for the Edge filter

After applying the filter (Sobel option)


Figure 17.140. Applying examples for the Edge filter

Applying examples for the Edge filter

After applying the filter (Prewitt compass option)

Applying examples for the Edge filter

After applying the filter (Gradient option)


Figure 17.141. Applying example for the Edge filter

Applying example for the Edge filter

After applying the filter (Roberts option)

Applying example for the Edge filter

After applying the filter (Differential option)


Figure 17.142. Applying example for the Edge filter

Applying example for the Edge filter

After applying the filter (Laplace option)


8.3.2. Activating the filter

You can find this filter through FiltersEdge-DetectEdge….

8.3.3. Options

Figure 17.143. Edge filter options

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 compass

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.