Summary. In this chapter, we introduce some recently developed fuzzy based techniques for image segmentation. They are fuzzy thresholding, fuzzy rule-based inferencing scheme, fuzzy c-mean clustering, and fuzzy integral-based decision making. A fuzzy integral based region merging algorithm for image segmentation, which combines both region and edge features of the image, is then used to merge regions recursively according to the criterion of the maximum fuzzy integral. The region merging process is regarded as a nonlinear process that fuses objective evidence, in the form of a fuzzy membership function that reflects the similarities between adjacent regions with respect to each feature, with the apriori system's expectation of the importance of that evidence provided by the corresponding feature. Using the maximum fuzzy integral criterion, the target number of regions can be reached by recursively merging regions. To handle the parameter initiation problem faced in the computation of fuzzy integral, an algorithm for automatically choosing such parameters is formulated as an optimization problem. A simulated annealing algorithm is designed to explore the value space offuzzy densities and search the (near) optimal solution corresponding to a minimum cost value. This way, fuzzy densities are determined adaptively depending on the image at hand without requiring any human intervention. To evaluate the performance of the proposed approach, it is applied to magnetic resonance images (MRI) and natural images. The experimental results have demonstrated that the proposed approach brings out robust segmentation performance and outperforms other approaches efficiently.