You can perform rotation operation on an image using the warpAffine() method of the imgproc class. Following is the syntax of this method −
Imgproc.warpAffine(src, dst, rotationMatrix, size);
This method accepts the following parameters −
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src − A Mat object representing the source (input image) for this operation.
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dst − A Mat object representing the destination (output image) for this operation.
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rotationMatrix − A Mat object representing the rotation matrix.
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size − A variable of the type integer representing the size of the output image.
Example
The following program demonstrates how to rotate an image.
import org.opencv.core.Core; import org.opencv.core.Mat; import org.opencv.core.Point; import org.opencv.core.Size; import org.opencv.imgcodecs.Imgcodecs; import org.opencv.imgproc.Imgproc; public class Rotation { public static void main(String args[]) { // Loading the OpenCV core library System.loadLibrary( Core.NATIVE_LIBRARY_NAME ); // Reading the Image from the file and storing it in to a Matrix object String file ="E:/OpenCV/chap24/transform_input.jpg"; Mat src = Imgcodecs.imread(file); // Creating an empty matrix to store the result Mat dst = new Mat(); // Creating a Point object Point point = new Point(300, 200) // Creating the transformation matrix M Mat rotationMatrix = Imgproc.getRotationMatrix2D(point, 30, 1); // Creating the object of the class Size Size size = new Size(src.cols(), src.cols()); // Rotating the given image Imgproc.warpAffine(src, dst, rotationMatrix, size); // Writing the image Imgcodecs.imwrite("E:/OpenCV/chap24/rotate_output.jpg", dst); System.out.println("Image Processed"); } }
Assume that following is the input image transform_input.jpg specified in the above program.
Output
On executing the program, you will get the following output −
Image Processed
If you open the specified path, you can observe the output image as follows −
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