Add algorithm to rotate images

digital_image_processing/rotation/rotation.py

@@ -0,0 +1,50 @@
+from matplotlib import pyplot as plt
+from numpy import float32
+import cv2
+
+
+def get_rotation(img, pt1, pt2, rows, cols):
+    """
+    Get image rotation
+    :param img: np.array
+    :param pt1: 3x2 list
+    :param pt2: 3x2 list
+    :param rows: columns image shape
+    :param cols: rows image shape
+    :return: np.array
+    """
+    matrix = cv2.getAffineTransform(pt1, pt2)
+    return cv2.warpAffine(img, matrix, (rows, cols))
+
+
+if __name__ == "__main__":
+    # read original image
+    image = cv2.imread("lena.jpg")
+    # turn image in gray scale value
+    gray_img = cv2.cvtColor(image, cv2.COLOR_BGR2GRAY)
+    # get image shape
+    img_rows, img_cols = gray_img.shape
+
+    # set different points to rotate image
+    pts1 = float32([[50, 50], [200, 50], [50, 200]])
+    pts2 = float32([[10, 100], [200, 50], [100, 250]])
+    pts3 = float32([[50, 50], [150, 50], [120, 200]])
+    pts4 = float32([[10, 100], [80, 50], [180, 250]])
+
+    # add all rotated images in a list
+    images = [
+        gray_img,
+        get_rotation(gray_img, pts1, pts2, img_rows, img_cols),
+        get_rotation(gray_img, pts2, pts3, img_rows, img_cols),
+        get_rotation(gray_img, pts2, pts4, img_rows, img_cols),
+    ]
+
+    # plot different image rotations
+    fig = plt.figure(1)
+    titles = ["Original", "Rotation 1", "Rotation 2", "Rotation 3"]
+    for i in range(0, len(images)):
+        plt.subplot(2, 2, i + 1), plt.imshow(images[i], "gray")
+        plt.title(titles[i])
+        plt.axis("off")
+        plt.subplots_adjust(left=0.0, bottom=0.05, right=1.0, top=0.95)
+    plt.show()