Diffusion coloring using weighted color points
An automated process provides diffusion coloring of vector graphics using color points, which appear to the user as color handles. A computing device programmatically receives input from a user establishing a plurality of color handles within a source geometry specified by a set of curves. The computing device defines a mesh with a plurality of vertices distributed throughout the source geometry. A resultant color at each vertex of the plurality of vertices is determined and a diffused pixel color is programmatically set for each pixel within the source geometry by interpolating between the resultant colors at the plurality of vertices.
1. A method comprising:
receiving, by a computing device, input from a user adding a plurality of color handles to a source graphical image specified by a set of curves;
establishing, by the computing device, the plurality of color handles so that each color handle is freely placeable within the source graphical image;
defining, by the computing device, a plurality of vertices distributed throughout the source graphical image;
determining, by the computing device, a resultant color at each vertex of the plurality of vertices by calculating a weighted sum of color values contributed by the plurality of color handles;
setting, by the computing device, a diffused pixel color for each pixel of a plurality of pixels within the source graphical image by interpolating between the resultant colors at the plurality of vertices; and
producing, by the computing device, a rendered geometry specified by the set of curves, the rendered geometry including the diffused pixel color for each pixel.
2. The method of claim 1 wherein the input includes at least one of a color handle color, a color handle weight, a color handle position, or a change to one or more of the foregoing.
3. The method of claim 1 wherein the input includes a quality parameter and wherein the weighted sum of color values is determined by a solution to a harmonic, bi-harmonic, or tri-harmonic equation as determined by the quality parameter.
4. The method of claim 1 wherein the plurality of vertices correspond to points in a triangular mesh, and wherein the method further comprises producing the triangular mesh by conforming Delaunay triangulation and bounded by a clipping path based on boundaries of the source graphical image.
5. The method of claim 4 wherein a position of each color handle of the plurality of color handles is defined by a Steiner point.
6. The method of claim 1 wherein the set of curves comprises cubic Bezier splines.
7. The method of claim 1 wherein the input comprises a change to the source graphical image, and wherein the method further comprises recalculating the resultant color at each vertex of the plurality of vertices and resetting a diffused pixel color for each pixel of a plurality of pixels.
8. A system comprising:
a processor; and
a non-transitory computer-readable medium coupled to the processor, wherein the processor is configured to execute computer program code stored in the non-transitory computer-readable medium and thereby perform operations comprising:
receiving input from a user adding a plurality of color handles to a source graphical image specified by a set of curves;
establishing the plurality of color handles so that each color handle is freely placeable within the source graphical image;
defining a plurality of vertices distributed throughout the source graphical image;
determining, by the computing device, a resultant color at each vertex of the plurality of vertices by calculating a weighted sum of color values contributed by the plurality of color handles;
setting, by the computing device, a diffused pixel color for each pixel of a plurality of pixels within the source graphical image by interpolating between the resultant colors at the plurality of vertices; and
producing, by the computing device, a rendered geometry specified by the set of curves, the rendered geometry including the diffused pixel color for each pixel.
9. The system of claim 8 wherein the input includes at least one of a color handle color, a color handle weight, a color handle position, or a change to one or more of the foregoing.
10. The system of claim 8 wherein the input includes a quality parameter and wherein the weighted sum of color values is determined by a solution to a harmonic, bi-harmonic, or tri-harmonic equation as determined by the quality parameter.
11. The system of claim 8 wherein the plurality of vertices correspond to points in a triangular mesh, and wherein the operations further comprise producing the triangular mesh by conforming Delaunay triangulation and bounded by a clipping path based on boundaries of the source graphical image.
12. The system of claim 11 wherein a position of each color handle of the plurality of color handles is defined by a Steiner point.
13. The system of claim 8 wherein the input comprises a change to the source graphical image, and wherein the operations further comprise recalculating the resultant color at each vertex of the plurality of vertices and resetting a diffused pixel color for each pixel of a plurality of pixels.
14. A non-transitory computer-readable medium storing program code executable by a processor to perform operations, the operations comprising:
receiving input from a user adding a plurality of color handles to a source graphical image specified by a set of curves;
establishing the plurality of color handles so that each color handle is freely placeable within the source graphical image;
defining a plurality of vertices distributed throughout the source graphical image;
determining, by the computing device, a resultant color at each vertex of the plurality of vertices by calculating a weighted sum of color values contributed by the plurality of color handles;
setting, by the computing device, a diffused pixel color for each pixel of a plurality of pixels within the source graphical image by interpolating between the resultant colors at the plurality of vertices; and
producing, by the computing device, a rendered geometry specified by the set of curves, the rendered geometry including the diffused pixel color for each pixel.
15. The non-transitory computer-readable medium of claim 14 wherein the input includes at least one of a color handle color, a color handle weight, a color handle position, or a change to one or more of the foregoing.
16. The non-transitory computer-readable medium of claim 14 wherein the input includes a quality parameter and wherein the weighted sum of color values is determined by a solution to a harmonic, bi-harmonic, or tri-harmonic equation as determined by the quality parameter.
17. The non-transitory computer-readable medium of claim 14 wherein the plurality of vertices correspond to points in a triangular mesh, and wherein the operations further comprise producing the triangular mesh by conforming Delaunay triangulation and bounded by a clipping path based on boundaries of the source graphical image.
18. The non-transitory computer-readable medium of claim 17 wherein a position of each color handle of the plurality of color handles is defined by a Steiner point.
19. The non-transitory computer-readable medium of claim 14 wherein the set of curves comprises cubic Bezier splines.
20. The non-transitory computer-readable medium of claim 14 wherein the input comprises a change to the source graphical image, and wherein the operations further comprise recalculating the resultant color at each vertex of the plurality of vertices and resetting a diffused pixel color for each pixel of a plurality of pixels.