An image processing system for identifying table captions may include a processor and a non-transitory computer-readable storage medium comprising one or more instructions configured to cause the processor to perform image processing of a scanned document to identify boxes of an electronic fillable form that corresponds to the scanned document. The system creates and stores a data structure that includes a box list. The system searches the box list to identify an empty box, uses an adjacency list determine whether the empty box has adjacent boxes, and in response to determining that the empty box has one or more adjacent boxes, creates a table box list that includes the empty box and one or more other boxes from the table to which the empty box belongs. The system uses the adjacency list to identify a row caption and a column caption associated with the empty box.