1. A method of analyzing an image, including a first stage and a second stage, wherein the first stage includes: inputting a pixel block, which includes a limited number of pixels that are adjacent to one another in more than one dimension, as a single unit from data including a plurality of pixels for forming an image, together with an adjacent pixel group including pixels that are adjacent to the pixel block and have already been labeled; labeling, based on binarized pixels, all on-pixels or all off-pixels that are subject for grouping included in a pixel block with common identification information, the common identification information being an inherited identification when the adjacent pixel group includes inheritable identification information and connecting information is recorded when the adjacent pixel group includes other inheritable identification information, or new identification information when the adjacent pixel group does not include inheritable identification information; and calculating block characteristic values of the pixel block, and wherein the second stage includes, calculating characteristic values of respective image elements composed of pixel blocks that have identification information connected by the connecting information with calculating total of the block characteristic values of the pixel blocks that have identification information connected by the connecting information.