skew.py

import numpy as np
import argparse
import cv2

ap = argparse.ArgumentParser()
ap.add_argument("-i", "--image", required=True,
                help="path to input image file")
args = vars(ap.parse_args())

image = cv2.imread(args["image"])

gray = cv2.cvtColor(image, cv2.COLOR_BGR2GRAY)
gray = cv2.bitwise_not(gray)

thresh = cv2.threshold(gray, 0, 255,
                       cv2.THRESH_BINARY | cv2.THRESH_OTSU)[1]

coords = np.column_stack(np.where(thresh > 0))
angle = cv2.minAreaRect(coords)[-1]

if angle < -45:
    angle = -(90 + angle)

else:
    angle = -angle

(h, w) = image.shape[:2]
center = (w // 2, h // 2)
M = cv2.getRotationMatrix2D(center, angle, 1.0)
rotated = cv2.warpAffine(image, M, (w, h),
                         flags=cv2.INTER_CUBIC, borderMode=cv2.BORDER_REPLICATE)

cv2.putText(rotated, "Angle: {:.2f} degrees".format(angle),
            (10, 30), cv2.FONT_HERSHEY_SIMPLEX, 0.7, (0, 0, 255), 2)

print("[INFO] angle: {:.3f}".format(angle))
cv2.imshow("Input", image)
cv2.imshow("Rotated", rotated)
cv2.waitKey(0)