diff --git a/reference_manual/filters/edge_detection.rst b/reference_manual/filters/edge_detection.rst index 5e9c40edc..e2a277f2b 100644 --- a/reference_manual/filters/edge_detection.rst +++ b/reference_manual/filters/edge_detection.rst @@ -1,93 +1,93 @@ .. meta:: :description: Overview of the edge detection filters. .. metadata-placeholder :authors: - Wolthera van Hövell tot Westerflier - Raghavendra Kamath :license: GNU free documentation license 1.3 or later. .. index:: Edge Detection, Sobel, Prewitt .. _edge_detection_filters: ============== Edge Detection ============== Edge detection filters focus on finding sharp contrast or border between colors in an image to create edges or lines. Since 4.0 there are only two edge detection filters. Edge Detection -------------- .. versionadded:: 4.0 A general edge detection filter that encapsulates all other filters. Edge detection filters that were separate before 4.0 have been folded into this one. It is also available for filter layers and filter brushes. .. figure:: /images/filters/Krita_4_0_edge_detection.png :align: center :figwidth: 800 - From left to right: Original, with prewitt edge detection applied, with prewitt edge detection applied and result applied to alpha channel, and finally the original with an edge detection filter layer with the same settings as 3, and the filter layer blending mode set to multiply + From left to right: Original, with Prewitt edge detection applied, with Prewitt edge detection applied and result applied to alpha channel, and finally the original with an edge detection filter layer with the same settings as 3, and the filter layer blending mode set to multiply Formula The convolution kernel formula for the edge detection. The difference between these is subtle, but still worth experimenting with. Simple A Kernel that is not square unlike the other two, and while this makes it fast, it doesn't take diagonal pixels into account. Prewitt A square kernel that includes the diagonal pixels just as strongly as the orthogonal pixels. Gives a very strong effect. - Sobol + Sobel A square kernel that includes the diagonal pixels slightly less strong than the orthogonal pixels. Gives a more subtle effect than Prewitt. Output The output. All sides Convolves the edge detection into all directions and combines the result with the Pythagorean theorem. This will be good for most uses. Top Edge This only detects changes going from top to bottom and thus only has top lines. Bottom Edge This only detects changes going from bottom to top and thus only has bottom lines. Right Edge This only detects changes going from right to left and thus only has right lines. Left Edge This only detects changes going from left to right and thus only has left lines. Direction in Radians This convolves into all directions and then tries to output the direction of the line in radians. Horizontal/Vertical radius The radius of the edge detection. Default is 1 and going higher will increase the thickness of the lines. Apply result to Alpha Channel. The edge detection will be used on a grayscale copy of the image, and the output will be onto the alpha channel of the image, meaning it will output lines only. .. index:: Height Map, Normal Map Height to Normal Map -------------------- .. versionadded:: 4.0 .. image:: /images/filters/Krita_4_0_height_to_normal_map.png :align: center A filter that converts Height maps to Normal maps through the power of edge detection. It is also available for the filter layer or filter brush. Formula The convolution kernel formula for the edge detection. The difference between these is subtle, but still worth experimenting with. Simple A Kernel that is not square unlike the other two, and while this makes it fast, it doesn't take diagonal pixels into account. Prewitt A square kernel that includes the diagonal pixels just as strongly as the orthogonal pixels. Gives a very strong effect. - Sobol + Sobel A square kernel that includes the diagonal pixels slightly less strong than the orthogonal pixels. Gives a more subtle effect than Prewitt. Channel Which channel of the layer should be interpreted as the grayscale heightmap. Horizontal/Vertical radius The radius of the edge detection. Default is 1 and going higher will increase the strength of the normal map. Adjust this if the effect of the resulting normal map is too weak. XYZ - An XYZ swizzle, that allows you to map Red, Green and Blue to different 3d normal vector coordinates. This is necessary mostly for the difference between Mikkt-space normal maps (+X, +Y, +Z) and the OpenGL standard normal map (+X, -Y, +Z). + An XYZ swizzle, that allows you to map Red, Green and Blue to different 3d normal vector coordinates. This is necessary mostly for the difference between MikkT-space normal maps (+X, +Y, +Z) and the OpenGL standard normal map (+X, -Y, +Z).