/**
* 合同圖片中公章提取
* 1) 輸入與輸出都為PNG高保真影像
* 2) compile: g++ -g -o sealcut sealcut.cpp `pkg-config --cflags --libs opencv`
* 3) usage: sealcut filename
*
* @yangxf
* @date 2018-03
*/
#include <opencv2/opencv.hpp>
#include <vector>
#include <iostream>
#include <stdio.h>
#include <unistd.h>
#include <dirent.h>
#include <stdlib.h>
#include <sys/stat.h>
#include <string.h>
using namespace std;
using namespace cv;
const char* windowname = "sealcut Demo";
const char* sealimgpath = "./sample";
const char* benchmarkpath = "./benchmark";
// 紅色閾值
int hsvredlovalue = 140;
int hsvredhivalue = 250;
// 公章半徑
int sealredius=154;
// 影像預處理
Mat initimage(char* imgname);
// 采用輪廓中的五角星定位公章影像:該演算法對于五角星不明顯的印章效果不佳
vector<Rect> locsealbycontours(Mat hqimg);
// 采用霍夫圓擬近圓形定位公章影像:該演算法普適性較高,可以定位到影像中的所有圓形
vector<Rect> locsealbyhough(Mat hqimg);
// 公章影像切割
void cutseal(Mat srcimg, vector<Rect> rects, char* imgname);
// 霍夫圓變換
void houghseal(Mat srcimg, int index, char* imgname);
// 采用閾值法剔除紅色公章,獲得自由文字和簽字的合同頁
Mat maskimage(char* imgname);
int main( int argc, char** argv ) {
if(argc != 2) {
cout << " usage: sealocr filename, please input image file name!" << endl;
return 0;
}
char imgpath[200], srcimgname[200];
memset(imgpath, 0, sizeof(imgpath));
memset(srcimgname, 0, sizeof(srcimgname));
sprintf(srcimgname, "%s", argv[1]);
sprintf(imgpath, "%s/%s", sealimgpath, srcimgname);
cout << imgpath << endl;
// 影像增強
Mat imageGamma=initimage(imgpath);
// 采用霍夫圓擬近圓形定位公章影像
vector<Rect> rects=locsealbyhough(imageGamma);
// 采用輪廓中的五角星定位公章影像, 該演算法效果不佳,暫不用
// vector<Rect> rects= locseal(imageGamma);
// 根據grabcut實作公章影像提取
cutseal(imageGamma, rects, srcimgname);
// 如果需要除錯,請打開如下陳述句
//waitKey();
return 1;
}
/**
* 影像預處理
* 1) 加載影像檔案
* 2) 影像增強
*
*/
Mat initimage(char* imgname) {
Mat srcimg = imread(imgname);
namedWindow("srcimg",CV_WINDOW_NORMAL);
imshow("srcimg", srcimg);
// Gamma影像增強: 解決印章模糊不清的問題
Mat imageGamma(srcimg.size(), CV_32FC3);
for (int i = 0; i < srcimg.rows; i++) {
for (int j = 0; j < srcimg.cols; j++) {
imageGamma.at<Vec3f>(i, j)[0] = (srcimg.at<Vec3b>(i, j)[0])*(srcimg.at<Vec3b>(i, j)[0])*(srcimg.at<Vec3b>(i, j)[0]);
imageGamma.at<Vec3f>(i, j)[1] = (srcimg.at<Vec3b>(i, j)[1])*(srcimg.at<Vec3b>(i, j)[1])*(srcimg.at<Vec3b>(i, j)[1]);
imageGamma.at<Vec3f>(i, j)[2] = (srcimg.at<Vec3b>(i, j)[2])*(srcimg.at<Vec3b>(i, j)[2])*(srcimg.at<Vec3b>(i, j)[2]);
}
}
// 歸一化到0~255
normalize(imageGamma, imageGamma, 0, 255, CV_MINMAX);
// 轉換成8bit影像
convertScaleAbs(imageGamma, imageGamma);
//namedWindow("imageGamma",CV_WINDOW_NORMAL);
//imshow("imageGamma", imageGamma);
return imageGamma;
}
// 采用霍夫圓擬近圓形定位公章影像
vector<Rect> locsealbyhough(Mat hqimg) {
// RGB顏色轉換為HSV
Mat hsvimage;
cvtColor(hqimg, hsvimage, COLOR_BGR2HSV);
// 閾值操作:查找指定范圍內的顏色
Mat dstimage;
inRange(hsvimage, Scalar( hsvredlovalue, 40, 40), Scalar (hsvredhivalue, 255, 255), dstimage);
// 查找輪廓
vector<vector<Point> > contours;
findContours(dstimage, contours, CV_RETR_CCOMP, CV_CHAIN_APPROX_SIMPLE);
namedWindow("findContours",CV_WINDOW_NORMAL);
imshow("findContours", dstimage);
// 將輪廓渲染為紅色
vector<Rect> rects;
Mat drawimage = Mat::zeros(dstimage.size(), CV_8UC3);
for(int index = 0; index < contours.size(); index ++) {
vector<Point> dstcontour=contours[index];
drawContours(drawimage, contours, index, Scalar(0, 0, 255), 3, 8);
}
namedWindow("drawimage", CV_WINDOW_NORMAL);
imshow("drawimage", drawimage);
// 轉為灰度圖,進行影像平滑
Mat graymage;
cvtColor(drawimage, graymage, CV_BGR2GRAY);
GaussianBlur(graymage, graymage, Size(9, 9), 2, 2);
// 霍夫圓變換:去掉公章圓外部的噪聲塊
Mat houghimage=Mat::zeros(drawimage.size(), CV_8UC3);
vector<Vec3f> circles;
HoughCircles(graymage, circles, CV_HOUGH_GRADIENT, 2/*霍夫空間的解析度*/, 300/*兩個圓心之間最小距離*/, 100/*Canny閾值*/, 25, 100/*最小半徑*/, 300/*最大半徑*/);
Point center;
int radius=0;
cout << "hough circles " << circles.size() << endl;
for(size_t i = 0; i < circles.size(); i++) {
center=Point(cvRound(circles[i][0]), cvRound(circles[i][1]));
radius = cvRound(circles[i][2]);
if(radius < 130 || radius > 160)
continue;
cout << "locsealbyhough hough center " << center << endl;
cout << "locsealbyhough hough radius " << radius << endl;
//測驗: 繪制圓心
circle(houghimage, center, 3, Scalar(0, 255, 0), -1, 8, 0);
//測驗: 繪制圓輪廓
circle(houghimage, center, radius, Scalar(155, 50, 255), 3, 8, 0);
rects.push_back(Rect(center.x - sealredius, center.y - sealredius, sealredius*2, sealredius*2));
}
namedWindow("houghseal", CV_WINDOW_NORMAL);
imshow("houghseal", houghimage);
return rects;
}
/**
* 采用輪廓中的五角星定位公章影像
* 1) 采用HSV顏色閾值查找影像輪廓:公章影像是紅色的
* 2) 根據輪廓形態定位五角星位置,并計算出公章的矩形
*
*/
vector<Rect> locsealbycontours(Mat hqimg) {
// RGB顏色轉換為HSV
Mat hsvimage;
cvtColor(hqimg, hsvimage, COLOR_BGR2HSV);
//namedWindow("hsvimage", CV_WINDOW_NORMAL);
//imshow("hsvimage", hsvimage);
// 影像腐蝕和膨脹
/*
dilate(hsvimage, hsvimage, Mat(7,7,CV_8U), Point(-1,-1), 2);
erode(hsvimage, hsvimage, Mat(8,8,CV_8U), Point(-1,-1), 1);
namedWindow("hsvimage2",CV_WINDOW_NORMAL);
imshow("hsvimage2", HSVImage);
*/
// 閾值操作:查找指定范圍內的顏色
Mat dstimage;
inRange(hsvimage, Scalar( hsvredlovalue, 40, 40), Scalar (hsvredhivalue, 255, 255), dstimage);
// 轉換成二值圖
/*
threshold(dstimage, dstimage, 1, 255, THRESH_BINARY);
namedWindow("dstimage",CV_WINDOW_NORMAL);
imshow(window_name, dstimage);
*/
// 查找輪廓
vector<vector<Point> > contours;
findContours(dstimage, contours, CV_RETR_CCOMP, CV_CHAIN_APPROX_SIMPLE);
//namedWindow("findContours",CV_WINDOW_NORMAL);
//imshow("findContours", dstimage);
// 定位公章影像
vector<Rect> rects;
Mat drawimage = Mat::zeros(dstimage.size(), CV_8UC3);
for(int index = 0; index < contours.size(); index ++) {
vector<Point> dstcontour=contours[index];
// 測驗:為了能看到公章影像效果
drawimage = Mat::zeros(dstimage.size(), CV_8UC3);
drawContours(drawimage, contours, index, Scalar(0, 0, 255), 3, 8);
// 輪廓面積
int area= int(fabs(contourArea( dstcontour )));
// 【重要】根據輪廓形態找到五角星(公章中間都有五角星):面積>1000, 40<外接圓半徑<60
if(area < 1000) {
continue;
}
Point2f center; float radius;
minEnclosingCircle(dstcontour, center, radius);
if(radius < 40 || radius > 60)
continue;
cout << "area " << area << endl;
cout << "radius " << radius << endl;
// 測驗:畫輪廓的外接圓
//circle(drawimage, center, (int)radius, Scalar(255, 0, 0), 2, 8, 0);
// 根據五角星中心點找到印章半徑:印章半徑值=154
circle( drawimage, center, sealredius, Scalar(0, 255, 0), 2, 8, 0 );
// 測驗:是否為印章的外接矩形
//rectangle(drawimage, Point(center.x - 154, center.y - 154), Point(center.x + 154, center.y + 154), Scalar( 255, 0, 0), -1, 8);
rects.push_back(Rect(center.x - sealredius, center.y - sealredius, sealredius*2, sealredius*2));
}
//namedWindow("sealocr", CV_WINDOW_NORMAL);
//imshow("sealocr", drawimage);
return rects;
}
/**
* 公章影像切割
* 1) 采用grabCut演算法實作公章影像自動切割
*/
void cutseal(Mat srcimg, vector<Rect> rects, char* imgname) {
Mat bgModel;
Mat fgModel;
// 設定掩碼影像
Mat result = cv::Mat::ones(srcimg.size(), CV_8U) * cv::GC_BGD;
for(int i = 0; i < rects.size(); i ++) {
Rect rect=rects[i];
// 設定前景掩碼
rectangle(result, rect , cv::Scalar(cv::GC_PR_FGD), -1, 8, 0);
}
Rect rect;
grabCut(srcimg, result, rect, bgModel, fgModel, 1, GC_INIT_WITH_MASK);
// 得到前景mask
compare(result, GC_PR_FGD, result, CMP_EQ);
Mat foreground(srcimg.size(), CV_8UC3, Scalar::all(255));
srcimg.copyTo(foreground, result);
namedWindow("foreground", CV_WINDOW_NORMAL);
imshow("foreground", foreground);
for(int index = 0; index < rects.size(); index ++) {
Rect rect=rects[index];
cout << "index " << index << endl;
// 設定公章影像ROI
Mat fgroi(foreground, rect);
char winname[100];
sprintf(winname, "cutseal reslut %d", index);
namedWindow(winname, CV_WINDOW_NORMAL);
imshow(winname, fgroi);
houghseal(fgroi, index, imgname);
}
}
/**
* 霍夫圓變換
* 1) 根據Hough圓變換找到標準的圓
* 2) 剔除圓意外的其他噪聲干擾
*
*/
void houghseal(Mat srcimg, int index, char* imgname) {
// 轉為灰度圖,進行影像平滑
Mat graymage;
cvtColor(srcimg, graymage, CV_BGR2GRAY);
GaussianBlur(graymage, graymage, Size(9, 9), 2, 2);
// 霍夫圓變換:去掉公章圓外部的噪聲塊
Mat houghimage=Mat::zeros(srcimg.size(), CV_8UC3);
vector<Vec3f> circles;
//HoughCircles(graymage, circles, CV_HOUGH_GRADIENT, 2/*霍夫空間的解析度*/, sealredius/*兩個圓心之間最小距離*/, 200/*Canny閾值*/, 100, 100/*最小半徑*/, 200/*最大半徑*/);
HoughCircles(graymage, circles, CV_HOUGH_GRADIENT, 2/*霍夫空間的解析度*/, 300/*兩個圓心之間最小距離*/, 100/*Canny閾值*/, 25, 100/*最小半徑*/, 300/*最大半徑*/);
Point center;
int radius=0;
cout << "hough circles " << circles.size() << endl;
for(size_t i = 0; i < circles.size(); i++) {
center=Point(cvRound(circles[i][0]), cvRound(circles[i][1]));
radius = cvRound(circles[i][2]);
cout << "hough center " << center << endl;
cout << "hough radius " << radius << endl;
// 圓心與影像中心點距離太遠
if(abs(center.x - sealredius) > 20 || abs(center.y - sealredius) >20) {
// Hough檢測到非完整的圓(超出影像邊界),忽略
return;
}
//測驗: 繪制圓心
circle(houghimage, center, 3, Scalar(0, 255, 0), -1, 8, 0);
//測驗: 繪制圓輪廓
circle(houghimage, center, radius, Scalar(155, 50, 255), 3, 8, 0);
}
char winname[100];
sprintf(winname, "houghseal reslut %d", index);
namedWindow(winname, CV_WINDOW_NORMAL);
imshow(winname, houghimage);
// 建立圓形腌膜剔除其他噪聲
Mat circleimg(srcimg.size(), CV_8UC1, Scalar(0));
// mask建立
Mat roi = Mat::zeros(srcimg.size(), CV_8UC3);
circle(roi, center, radius + 20, CV_RGB(255, 255, 255), -1);
srcimg.copyTo(circleimg, roi);
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