Decomposing Images into Layers with Advanced Color Blending

Digital paintings are often created by compositing semi‐transparent layers using various advanced color‐blend modes, such as “color‐burn,” “multiply,” and “screen,” which can produce interesting non‐linear color effects. We propose a method of decomposing an input image into layers with such advanced color blending. Unlike previous layer‐decomposition methods, which typically support only linear color‐blend modes, ours can handle any user‐specified color‐blend modes. To enable this, we generalize a previous color‐unblending formulation, in which only a specific layering model was considered. We also introduce several techniques for adapting our generalized formulation to practical use, such as the post‐processing for refining smoothness. Our method lets users explore possible decompositions to find the one that matches for their purposes by manipulating the target color‐blend mode and desired color distribution for each layer, as well as the number of layers. Thus, the output of our method is a layered, easily editable image composition organized in a way that digital artists are familiar with. Our method is useful for remixing existing illustrations, flexibly editing single‐layer paintings, and bringing physically painted media (e.g., oil paintings) into a digital workflow.