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/*
This tutorial demonstrates how to correct the skewness in a text.
The program takes as input a skewed source image and shows non skewed text.
*/
#include <opencv2/core.hpp>
#include <opencv2/imgcodecs.hpp>
#include <opencv2/highgui.hpp>
#include <opencv2/imgproc.hpp>
#include <iostream>
#include <iomanip>
#include <string>
using namespace cv;
using namespace std;
int main( int argc, char** argv )
{
CommandLineParser parser(argc, argv, "{@input | imageTextR.png | input image}");
// Load image from the disk
Mat image = imread( samples::findFile( parser.get<String>("@input") ), IMREAD_COLOR);
if (image.empty())
{
cout << "Cannot load the image " + parser.get<String>("@input") << endl;
return -1;
}
Mat gray;
cvtColor(image, gray, COLOR_BGR2GRAY);
//Threshold the image, setting all foreground pixels to 255 and all background pixels to 0
Mat thresh;
threshold(gray, thresh, 0, 255, THRESH_BINARY_INV | THRESH_OTSU);
// Applying erode filter to remove random noise
int erosion_size = 1;
Mat element = getStructuringElement( MORPH_RECT, Size(2*erosion_size+1, 2*erosion_size+1), Point(erosion_size, erosion_size) );
erode(thresh, thresh, element);
cv::Mat coords;
findNonZero(thresh, coords);
RotatedRect box = minAreaRect(coords);
float angle = box.angle;
// The cv::minAreaRect function returns values in the range [-90, 0)
// if the angle is less than -45 we need to add 90 to it
if (angle < -45.0f)
{
angle = (90.0f + angle);
}
//Obtaining the rotation matrix
Point2f center((image.cols) / 2.0f, (image.rows) / 2.0f);
Mat M = getRotationMatrix2D(center, angle, 1.0f);
Mat rotated;
// Rotating the image by required angle
stringstream angle_to_str;
angle_to_str << fixed << setprecision(2) << angle;
warpAffine(image, rotated, M, image.size(), INTER_CUBIC, BORDER_REPLICATE);
putText(rotated, "Angle " + angle_to_str.str() + " degrees", Point(10, 30), FONT_HERSHEY_SIMPLEX, 0.7, Scalar(0, 0, 255), 2);
cout << "[INFO] angle: " << angle_to_str.str() << endl;
//Show the image
imshow("Input", image);
imshow("Rotated", rotated);
waitKey(0);
return 0;
}
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