Lyric Edges Matte
The Lyric Edges Matte produces a matte that selects the edges of objects in a scene, essentially all the boundaries between between different colors. It is typically used as a filter mask, allowing you to apply adjustments just to the edges, such as sharpening or or emphasis, but it can be used to generate interesting line-drawing style effects.
The filter provides two alternative edge-detection methods: Soebel Convolution and Gaussian Differencing. See the section below on Edge-Detection Methods for discussion and examples of the two methods.
The Lyric Edges Matte filter includes a set of matte and output controls that are common across all Lyric matte filters. For a detailed description of these controls, please see the Matte Common Controls documentation.
For background information on mattes and their uses in Final Cut, please refer to the Lyric Matte Primer.
The Edges Matte has two alternative edge-detections methods, Soebel Convolution and Gaussian Difference, selectable in the Edge Method dropdown menu. See the Edge Detection Methods discussion below for details.
The Threshold slider controls the sensitivity of both edge methods; lower values reduce sensitivity, thinning out the edges, and higher values increase sensitivity such that more subtle differences in color are considered edges.
The Gaussian Edge Width slider is only active when the Gaussian Difference method is selected and it changes the radius of the gaussian blur. Higher values increase edge inclusion, lower values thin the edges. Lower gaussian values with higher threshold settings produce more defined edges.
The Matte Control and Output sections are common controls that are documented on the Matte Common Controls page.
The Edges Matte has two alternative edge-detections methods, Soebel Convolution and Gaussian Difference, selectable in the Edge Method dropdown menu.
Soebel Convolution uses a set of 4 special convolution kernels to produce a smooth, though somewhat broad edge matte. Since the convolver radius in Final Cut is fixed, there is no direct way to control edge width in the convolution, but both the Threshold control and the Choke/Expand control in the Matte Control section can give substantial control over edge definition.
Gaussian Differencing uses the same technique that the well-known Unsharp-mask sharpening filter uses. It takes a blurred version of an image and subtracts it from the original. Since broad, unchanging areas in the image remain similar under blurring, but edges soften and lose their definition, this subtraction results in all the broad areas disappearing, leaving the edges. It results in a harder, more sketched style of edge matte compared to Soebel Convolution and with higher blurring radii can include broader areas where there is nearby high-contrast within the radius.
The following examples show the same image with the alternative methods at the default settings.
Threshold = 0
Threshold = 0
Gaussian Edge Width = 15