Computer implemented method for recognizing answer sheet

A computer method for recognizing an answer sheet, comprising:

• reading a filled answer sheet comprising at least one set of graphical codes, wherein each set of graphical codes comprises at least one grid which is a square divided, by two diagonal lines, two center lines and four midpoint connecting lines connecting midpoints of four sides of the grid, into 16 triangular areas numbered in sequence, wherein each of the triangular areas is a filling area and each filling area has two states of filled state and un-filled state;
• locating each set of graphical codes in the answer sheet;
• reading, for each set of graphical codes, the state of each of the filling areas in a first grid of the set of graphical codes according to a number sequence of the filling areas, and obtaining, by means of representing the filled state as 1 and the un-filled state as 0, two sets of 8-digit binary codes composed of 16 digits;
• determining an encoding format corresponding to the graphical codes;
• and
• recognizing, based on at least the two sets of 8-digit binary codes and the encoding format, a character corresponding to the set of graphical codes.