A method for automatically selecting a number of Gaussian modes for segmentation of a cardiac magnetic resonance (MR) image, including: identifying a left ventricle (LV) in a cardiac MR image slice; quantifying the LV blood pool; obtaining a mask for the LV blood pool; generating a ring mask for a myocardium of the LV from the LV blood pool mask; fitting three Gaussian modes to a histogram of the image slice to obtain a corresponding homogeneity image for the myocardium; computing a quality of fitting (QOF) measure for the three Gaussian modes based on the corresponding homogeneity image; repeating the fitting and computing steps for four and five Gaussian modes; and selecting the homogeneity image of the number of Gaussian modes with the largest QOF measure as the homogeneity image for processing.