Example-based color transfer for gradient meshes

Editing a photo-realistic gradient mesh is a tough task. Even only editing the colors of an existing gradient mesh can be exhaustive and time-consuming. To facilitate user-friendly color editing, we develop an example-based color transfer method for gradient meshes, which borrows the color characteristics of an example image to a gradient mesh. We start by exploiting the constraints of the gradient mesh, and accordingly propose a linear-operator-based color transfer framework. Our framework operates only on colors and color gradients of the mesh points and preserves the topological structure of the gradient mesh. Bearing the framework in mind, we build our approach on PCA-based color transfer. After relieving the color range problem, we incorporate a fusion-based optimization scheme to improve color similarity between the reference image and the recolored gradient mesh. Finally, a multi-swatch transfer scheme is provided to enable more user control. Our approach is simple, effective, and much faster than color transferring the rastered gradient mesh directly. The experimental results also show that our method can generate pleasing recolored gradient meshes

Scribble-based gradient mesh recoloring

Previous gradient mesh recoloring methods usually have dependencies on an additional reference image and the rasterized gradient mesh. To circumvent such dependencies, we propose a user scribble-based recoloring method, in which users are allowed to annotate gradient meshes with a few color scribbles. Our approach builds an auxiliary mesh from gradient meshes, namely control net, by taking both colors and local color gradients at mesh points into account. We then develop an extended chrominance blending method to propagate the user specified colors over the control net. The recolored gradient mesh is finally reconstructed from the recolored control net. Experiments validate the effectiveness of our approach on multiple gradient meshes. Compared with various alternative solutions, our method has no color bleedings nor sampling artifacts, and can achieve fast performance

An Interactive Tool for Gamut Masking

Artists often want to change the colors of an image to achieve a particular aesthetic goal. For example, they might limit colors to a warm or cool color scheme to create an image with a certain mood or feeling. Gamut masking is a technique that artists use to limit the set of colors they can paint with. They draw a mask over a color wheel and only use the hues within the mask. However, creating the color palette from the mask and applying the colors to the image requires skill. We propose an interactive tool for gamut masking that allows amateur artists to create an image with a desired mood or feeling. Our system extracts a 3D color gamut from the 2D user-drawn mask and maps the image to this gamut. The user can draw a different gamut mask or locally refine the image colors. Our voxel grid gamut representation allows us to represent gamuts of any shape, and our cluster-based image representation allows the user to change colors locally

Locally refinable gradient meshes supporting branching and sharp colour transitions:Towards a more versatile vector graphics primitive

We present a local refinement approach for gradient meshes, a primitive commonly used in the design of vector illustrations with complex colour propagation. Local refinement allows the artist to add more detail only in the regions where it is needed, as opposed to global refinement which often clutters the workspace with undesired detail and potentially slows down the workflow. Moreover, in contrast to existing implementations of gradient mesh refinement, our approach ensures mathematically exact refinement. Additionally, we introduce a branching feature that allows for a wider range of mesh topologies, as well as a feature that enables sharp colour transitions similar to diffusion curves, which turn the gradient mesh into a more versatile and expressive vector graphics primitive