The median-shift, a new clustering algorithm, is proposed to automatically identify the palette of colored graphics, a pre-requisite for graphics vectorization. The median-shift is an iterative process which shifts each data point to the "median" point of its neighborhood defined thanks to a distance measure and a maximum radius, the only parameter of the method. The process is viewed as a graph transformation which converges to a set of clusters made of one or several connected vertices. As the palette identification depends on color perception, the clustering is performed in the L*a*b* feature space. As pixels located on edges are made of mixed colors not expected to be part of the palette, they are removed from the initial data set by an automatic pre-processing. Results are shown on scanned maps and on the Macbeth color chart and compared to well established methods.
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机译:建议中位转移,一种新的聚类算法,以自动识别彩色图形的调色板,是图形矢量化的先决条件。中位移是迭代过程,它将每个数据点移到其邻域的“中位数”,这是由于距离测量和最大半径,该方法的唯一参数。该过程被视为曲线图转换,该变换会聚到由一个或多个连接顶点制成的一组集群。由于调色板识别取决于颜色感知,因此在L * A * B *特征空间中执行聚类。由于位于边缘上的像素由未预期的混合颜色成为调色板的一部分,它们被自动预处理从初始数据中移除。结果显示在扫描地图上和Macbeth颜色图表上,并与成熟的方法相比。
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