Abstract: Tissue signatures are obtained from first and second order statistics of an image texture to discriminate between different normal tissues and to detect abnormal conditions. These signatures describe intrinsic backscatter properties of the tissue imaged, and are used as the basis of an automatic tissue characterization algorithm. A device for on-line classifying of the texture of an image measures a total of four first and second order statistical properties of echo signals of a region of interest (ROI) selected by an operator, the echo signals being contained in an image memory. These can be used to obtain the tissue signatures, to detect low contrast lesions by machine, and to produce parametric images.