An image processing method of identifying biological structures in a microscope image comprises: evaluating a first quantitative image metric based on the microscope image data associated with at least one image region to obtain first result data; performing a first comparison between the first result data and first comparator data, providing an indication of at least one candidate identity for a tissue structure in the at least one region, and determining whether structures in the microscope image data in the region can be classified based on the indication; and, in the event that the region cannot be classified based on the indication, selecting a second quantitative image metric based on at least one of: (i) the indication, and (ii) the first result data. Also claimed is use of a tissue type descriptor as well as tissue data storing an association between plural candidate structures, plural image metrics and comparator data (expected values of image metrics in candidates) values; and analogous methods omit
