A method for generating an image of a subsurface feature, comprises providing seismic data containing information about the feature, comprising i) a first dataset comprising a first up-going wave-field and a first down-going wave-field, ii) a second dataset comprising a second up-going wave-field and a second down-going wave-field, wherein the second dataset is collected at a time that is later than the first dataset by a time interval, creating an up-going 4D difference dataset U by subtracting one of the first and second up-going wave-fields from the other and creating a down-going 4D difference dataset D by subtracting one of the first and second down-going wave-fields from the other, creating a weighting function W that is a function of the similarity of the difference datasets, and creating an image of the feature by generating a 4D similarity stack, where the 4D similarity stack is defined as (U+D)*W/2.