一、简介
1、课题介绍：本课题为基于MATLAB的不变矩答题卡识别。可识别学号，学科，答案，并进行分数统计，以及判断是否及格。后台可设置标准excel答案。经过灰度变换形成灰度图像、二值化处理、图像滤波、边缘检测、hough变换等预处理。带GUI交互式界面。
2、识别原理：计算出了单选选择答案后，需要与标准的答案进行对比。这时需要建立一个二维的数组来储存标准答案。在程序中建立了一个数组，只有一行却有多个列，来记录每一道单项选择题的标准答案。记录好考生填涂的答案和标准答案后，这时通过一个 FOR 循环一一对比，如果相同的就让计数器加一如果不同计数器就不加。循环结束后就可以统计出考生选对的答案，然后将统计好。
二、源代码
clc; clear all; close all;
warning off all;
I = imread('images\\1.jpg');
I1 = Image_Normalize(I, 0);
hsize = [3 3];
sigma = 0.5;
I2 = Image_Smooth(I1, hsize, sigma, 0);
I3 = Gray_Convert(I2, 0);
bw2 = Image_Binary(I3, 0);
[~, ~, xy_long] = Hough_Process(bw2, I1, 0);
angle = Compute_Angle(xy_long);
[I4, bw3] = Image_Rotate(I1, bw2, angle*1.8, 0);
[bw4, Loc1] = Morph_Process(bw3, 0);
if nargin < 3
flag = 1;
end
[H, T, R] = hough(bw);
P = houghpeaks(H, 4, 'threshold', ceil(0.3*max(H(:))));
lines = houghlines(bw, T, R, P, 'FillGap', 50, 'MinLength', 7);
max_len = 0;
for k = 1 : length(lines)
xy = [lines(k).point1; lines(k).point2];
len = norm(lines(k).point1-lines(k).point2);
Len(k) = len;
if len > max_len
max_len = len;
xy_long = xy;
end
if nargin < 5
flag = 1;
end
Line1 = Line{1};
Line2 = Line{2};
Line3 = Line{3};
Line4 = Line{4};
yn1 = round(Line1(1, 2) + 0.18*(Line2(1, 2)-Line1(1, 2)));
yn2 = round(Line1(1, 2) + 0.34*(Line2(1, 2)-Line1(1, 2)));
yn3 = round(Line1(1, 2) + 0.50*(Line2(1, 2)-Line1(1, 2)));
Linen1_1 = [Line1(1, 1) yn1; Line1(2, 1) yn1];
Linen2_1 = [Line1(1, 1) yn2; Line1(2, 1) yn2];
Linen3_1 = [Line1(1, 1) yn3; Line1(2, 1) yn3];
% 定位竖直网格分割线
xn1 = round(Line3(1, 1) + 0.22*(Line4(1, 1)-Line3(1, 1)));
xn2 = round(Line3(1, 1) + 0.26*(Line4(1, 1)-Line3(1, 1)));
xn3 = round(Line3(1, 1) + 0.48*(Line4(1, 1)-Line3(1, 1)));
xn4 = round(Line3(1, 1) + 0.52*(Line4(1, 1)-Line3(1, 1)));
xn5 = round(Line3(1, 1) + 0.73*(Line4(1, 1)-Line3(1, 1)));
xn6 = round(Line3(1, 1) + 0.77*(Line4(1, 1)-Line3(1, 1)));
xn7 = round(Line3(1, 1) + 0.98*(Line4(1, 1)-Line3(1, 1)));
Linen1_2 = [xn1 Line3(1, 2); xn1 Line3(2, 2)];
Linen2_2 = [xn2 Line3(1, 2); xn2 Line3(2, 2)];
Linen3_2 = [xn3 Line3(1, 2); xn3 Line3(2, 2)];
Linen4_2 = [xn4 Line3(1, 2); xn4 Line3(2, 2)];
Linen5_2 = [xn5 Line3(1, 2); xn5 Line3(2, 2)];
Linen6_2 = [xn6 Line3(1, 2); xn6 Line3(2, 2)];
Linen7_2 = [xn7 Line3(1, 2); xn7 Line3(2, 2)];
ym1_1 = round(Line1(1, 2) + 0.32*(Linen1_1(1, 2)-Line1(1, 2)));
ym2_1 = round(Line1(1, 2) + 0.5*(Linen1_1(1, 2)-Line1(1, 2)));
ym3_1 = round(Line1(1, 2) + 0.65*(Linen1_1(1, 2)-Line1(1, 2)));
ym4_1 = round(Line1(1, 2) + 0.80*(Linen1_1(1, 2)-Line1(1, 2)));
ym5_1 = round(Line1(1, 2) + 0.95*(Linen1_1(1, 2)-Line1(1, 2)));
Linem1_1 = [Line1(1, 1) ym1_1; Line1(2, 1) ym1_1];
Linem2_1 = [Line1(1, 1) ym2_1; Line1(2, 1) ym2_1];
Linem3_1 = [Line1(1, 1) ym3_1; Line1(2, 1) ym3_1];
Linem4_1 = [Line1(1, 1) ym4_1; Line1(2, 1) ym4_1];
Linem5_1 = [Line1(1, 1) ym5_1; Line1(2, 1) ym5_1];
ym1_2 = round(Linen1_1(1, 2) + 0.25*(Linen2_1(1, 2)-Linen1_1(1, 2)));
ym2_2 = round(Linen1_1(1, 2) + 0.40*(Linen2_1(1, 2)-Linen1_1(1, 2)));
ym3_2 = round(Linen1_1(1, 2) + 0.60*(Linen2_1(1, 2)-Linen1_1(1, 2)));
ym4_2 = round(Linen1_1(1, 2) + 0.75*(Linen2_1(1, 2)-Linen1_1(1, 2)));
ym5_2 = round(Linen1_1(1, 2) + 0.90*(Linen2_1(1, 2)-Linen1_1(1, 2)));
Linem1_2 = [Line1(1, 1) ym1_2; Line1(2, 1) ym1_2];
Linem2_2 = [Line1(1, 1) ym2_2; Line1(2, 1) ym2_2];
Linem3_2 = [Line1(1, 1) ym3_2; Line1(2, 1) ym3_2];
Linem4_2 = [Line1(1, 1) ym4_2; Line1(2, 1) ym4_2];
Linem5_2 = [Line1(1, 1) ym5_2; Line1(2, 1) ym5_2];
end
三、运行结果
四、备注
版本：2014a
