1. A method of detecting and segmenting clusters of cells in an image, comprising: inputting image data I at a plurality of location (x,y) values, generating a variation map V(x,y) by performing a structure tensor analysis for calculating variations for one or more I(x,y) values, corresponding to an amount of change of said I(x,y) values relative to values at neighboring locations, along one or more directions, performing a multiscale decomposition of the variation map V(x,y) resulting in subband images at each scale, smoothing the variation map V(x,y) by combining subband images, and segmenting the smoothed variation map.