LoCoPalettes augments palette-based image editing with image-space constraints and semantic hierarchies. Left: The user places a spatial constraint on the input image to make the leaves brown. LoCoPalettes optimizes for a palette with respect to users’ image-space constraints, shown as small white circles. Center: The optimization updates the global palette. Right: The user places a second spatial constraint on the grass. If constraints cannot be satisfied with a single global palette, LoCoPalettes semantically segments the image and activates a palette hierarchy H to achieve the color constraints using local palettes. The grass constraint’s semantic segmentation mask is shown in the lower-right.
Palette-based image editing takes advantage of the fact that color palettes are intuitive abstractions of images. They allow users to make global edits to an image by adjusting a small set of colors. Many algorithms have been proposed to compute color palettes and corresponding mixing weights. However, in many cases, especially in complex scenes, a single global palette may not adequately represent all potential objects of interest. Edits made using a single palette cannot be localized to specific semantic regions. We introduce an adaptive solution to the usability problem based on optimizing RGB palette colors to achieve arbitrary image-space constraints and automatically splitting the image into semantic sub-regions with more representative local palettes when the constraints cannot be satisfied. Our algorithm automatically decomposes a given image into a semantic hierarchy of soft segments. Difficult-to-achieve edits become straightforward with our method. Our results show the flexibility, control, and generality of our method.
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@article{Chao:2023:CC, author = {Chao, Cheng-Kang Ted and Klein, Jason and Tan, Jianchao and Echevarria, Jose and Gingold, Yotam}, title = {{LoCoPalettes}: Local Control for Palette-based Image Editing}, journal = {Computer Graphics Forum (CGF)}, note = {Special issue for Eurographics Symposium on Rendering (EGSR)}, volume = {42}, number = {4}, year = {2023}, month = jun, keywords = {palette-based image editing, color, local, optimization, usability}, doi = {10.1111/cgf.14892} }