The disclosure relates to devices, systems and methods for generating a digital image of a tissue section that is a composite of two or more source digital images of adjacent tissue sections and which may have a real-time adjustable boundary between different source images. The devices include computer software products for a fused-view visualization tool which permits one or more of generating and displaying the composite image and modifying the location of one or more boundaries between source images comprising the composite image. The systems include computer-implemented systems such as work stations and networked computers for analyzing tissue samples using the fused-view visualization tool. The methods include processes for visualization of a tissue sample as a composite image derived from two or more slides of adjacent tissue sections, for example as an interactive composite image wherein the proportion of each source image in the composite image may be altered.