A new unsupervised color segmentation method based on region-constrained EM (Expectation Maximization) and graph cuts is proposed

which can automatically determine the number of segments for a color image.The proposed method first obtains the superpixels of the image and extracts CIE Lab color feature and multi-scale quaternion Gabor filter feature.In order to automatically and efficiently determine the number of segments for the image and avoid the problem caused by using superpixels directly

a window is used to sample each superpixel to obtain a pixel subset which represents the superpixel.Then the feature space of the sampled pixel subsets is modeled with Gaussian mixture model

and the model parame

ters (including the number of components) are obtained by a region-constraint component-wise EM algorithm.Finally

the segmentation result can be obtained by

-expansion with the learned model parameters.Experimental results demonstrate the good performance of the proposed method.