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A B S T R A C T The most valuable quantitative information contained in fatigue fracture surfaces is related to striations. An alternative source of information, in particular if striation identification is impossible, can be the general characteristics of fracture micromorphology evaluated by digital image analysis. For study of micrographs as image textures, new methods called textural fractography have been developed. In this paper, some of these methods and examples of their application are described. A generalization for the case of a variable cycle loading is proposed, based on a new concept of counting loading cycles. The presented work foreshadows the potential contribution of textural fractography for fractographic reconstitution of fatigue crack history.Keywords fatigue crack growth; image texture; quantitative fractography; variable cycle loading. N O M E N C L A T U R ES a = crack length a = crack increment in one cycle a cc = crack increment under constant cycle loading a real = crack increment under general loading B = harmonic wave C = vector of regression constants F = loading force F = matrix of image features f ij = j-th feature of i-th image h = effectivity of a loading cycle L = vector of logs of crack rates assigned to images N = number of loading cycles N ref = reference number of loading cycles p = period (wavelength) of a harmonic wave v = macroscopic fatigue crack growth rate v ref = RCGR, reference fatigue crack growth rate X = image of fracture surface x ij = local image brightness θ = orientation of a harmonic wave I N T R O D U C T I O NThe knowledge of the real history of a fatigue process is very valuable for design, development and reliable operation of structures exposed to time-variable loading service conditions. Information of this type can be obtained with