Answer sheet automatic grading method based on binary image connected domain statistics

Abstract

The invention provides an answer sheet automatic grading method based on binary image connected domain statistics. According to the answer sheet automatic grading method, after an answer sheet is scanned by a user and a positioning point is detected, binaryzation is carried out on an answering area; answers of all choice questions in an image are recognized and graded by adopting the answer sheet automatic grading method based on the binary image connected domain statistics, and finally answers of all questions and grades of all the questions are output. According to the method, filling points are located according to the positions of the filling points relative to marking points, and the method is not sensitive to inclination, shifting and slight wrinkles of the answer sheet in the process of scanning; whether the answer sheet is filled or not is judged by adopting a self-adaptation threshold value method, effective detection can be conducted on answers filled in different depths, the method can be suitable for both single-selection questions and multiple-selection questions, and the situation of unclean erasing and the situation of multiple-selection can be effectively distinguished. The user does not need to carry out answer sheet scanning again even after slight abnormal situations occur in the process of scanning, and therefore repeated operation can be reduced greatly.

Description

technical field [0001] The invention generally relates to the fields of computer pattern recognition and image processing, and in particular to an automatic scoring method for answer sheets based on statistics of connected domains of binary images. Background technique [0002] With the development of information technology, the amount of data processed by computers is increasing. In many fields, it is urgent to solve the problems of massive data collection, identification and input. At present, OMR (Optical Mark Reader) has been used to solve this problem in large-scale examinations such as the college entrance examination, the adult college entrance examination, and the National College English Level Examination. Although OMR technology has solved some problems of answer card data entry, but because its own technology is based on photoelectric recognition technology, there are many problems that are currently difficult to solve: (1) Equipment-specific: photoelectric recogn...

AI Technical Summary

Problems solved by technology

Although OMR technology has solved some problems of answer card data entry, but because its own technology is based on photoelectric recognition technology, there are many problems that are currently difficult to solve: (1) Equipment-specific: photoelectric recognition machines can only be used in reviewing objective questions , subjective questions still need to be scanned with a scanner, which is expensive; (2) The format of the answer sheet is fixed: limited by the relatively fixed installation position and arrangement density of the photoelectric head, it is very difficult to adjust the answer sheet of different formats, and even cannot meet the requirements; (3) The production cost of the answer sheet is high: the OMR answer sheet must be printed in color on lead-containing coated paper and has strict requirements on the cutting accuracy of the answer sheet. The economic and environmental costs are high, and most primary and secondary schools cannot afford the cost; ( 4) The error correction process is complicated: in the OMR technology, if an abnormality occurs during the recognition process, the machine must be shut down, and the wrong answer sheets must be manually sorted out, and manually refilled one by one before restarting the machine for recognition, which greatly affects the efficiency of marking.

(5) The image cannot be saved to be checked: the recognized answer sheet image cannot be saved, and the transparency of the judgment is poor. If you want to check it, you must manually sort it out from the paper answer sheet

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