A system and method are provided for testing electronic visual user interface outputs. The method includes obtaining a baseline set of one or more screen shots of a user interface, the user interface comprising one or more elements; generating an updated set of one or more screen shots of the user interface, the updated set comprising one or more changes to the user Interface; comparing the baseline set to the updated set to generate a differential set of one or more images illustrating differences in how at least one of the user interface elements is rendered. The comparing includes, for each screen shot: identifying coordinates of edges of a content portion of interest relative to an entire content captured in that screen shot; cropping the content portion using the coordinates from the baseline and updated versions of the entire content captured in that screen shot to obtain content portions of a same size for comparison; and performing a spatial unit-by-unit comparison of the same size cropped content portions to generate a differential image for that screen shot. The method also includes displaying the differential set of one or more images; and receiving an input validating the one or more changes to the user interface, or rejecting the one or more changes to the user interface.