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ZICQ Info Open Source AI #Palette Atlas #Color Scheme Search #HNSW Indexing #Sliced Wasserstein Embeddings #Open Source Tool

Palette Atlas Released: Efficient Color-Scheme-Based Painting Search System

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By Mr.Xu Community Post

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Summary:Reddit user Itzik123 has released Palette Atlas, a tool for efficiently searching public-domain paintings based on color schemes. The system reduces each image to 128 colors of equal weight and employs Sliced Wasserstein Embeddings with HNSW indexing to enable fast nearest-neighbor searches. It demonstrates superior performance in multiple benchmarks, significantly improving search accuracy and efficiency.


Technical Mechanism Analysis

Palette Atlas achieves the efficient color-scheme-based search through the following techniques:

  1. Color Simplification and Projection: Each painting is reduced to 128 colors of equal weight and represented in the OKLab color space. These colors are then projected onto 8 directions on a Fibonacci hemisphere.

  2. Sliced Wasserstein Embeddings: The colors are sorted and averaged into 16 quantiles, and the L1 distance between two vectors is calculated as a lower bound on the true Wasserstein distance. This approach significantly reduces computational complexity.

  3. HNSW Indexing: The system uses a hand-written HNSW (Hierarchical Navigable Small World) index structure with parameters M=16 and efConstruction=200. At a recall@10 of 1.000, the search time is only 0.25 milliseconds, compared to 14 milliseconds for brute-force search.

  4. Improved Top Layer Structure: Unlike the original paper, the top layer uses 8 k-means cluster centers as anchors instead of random nodes. This change keeps the search cost the same while ensuring that each color family corresponds to a typical painting.

Engineering Trade-offs and Performance

  • Performance Advantages: Compared to the traditional Earth Mover's Distance (EMD), Sliced Wasserstein Embeddings significantly improve computation speed while maintaining high search accuracy. In 240 queries, the overlap with the exact EMD is 78%, and the average distance to the top 10 results increases by only 1.8%.

  • Resource Efficiency: The intrinsic dimension of the HNSW index is about 11, indicating that the hierarchical structure is still effective in reducing computational complexity.

  • Limitations: Although the performance is excellent, the method may face challenges when dealing with very high-dimensional data or more complex color distributions. Additionally, the construction time of the HNSW index is long, which may not be suitable for real-time dynamic data updates.

Developer Implementation and Deployment Recommendations

  • Application Scenarios: Palette Atlas is suitable for applications that require fast image retrieval based on color schemes, such as art databases, digital libraries, and creative design tools.

  • Deployment Recommendations: Developers can refer to the GitHub code repository provided by Itzik123 for secondary development and adjust the color simplification parameters and HNSW index settings according to specific needs. For large-scale datasets, it is recommended to use distributed computing resources to accelerate the index construction process.

  • Optimization Directions: In the future, it is possible to explore the combination of deep learning technology to further improve the accuracy and robustness of color feature extraction. Additionally, the introduction of an adaptive index update mechanism can support dynamic data streams.


Source: Reddit r/MachineLearning (2026-10-11)

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Tags: #Palette Atlas #Color Scheme Search #HNSW Indexing #Sliced Wasserstein Embeddings #Open Source Tool

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