这是一个实现用于斜角估计的投影轮廓法算法 http://www.cvc.uab.es/%7Ebagdanov/pubs/ijdar98.pdf。各个角度点被投影到累加器阵列中,其中倾斜角可以被定义为最大化对准的搜索间隔内的投影角度。这个想法是以不同角度旋转图像并为每次迭代生成像素直方图。为了确定倾斜角度,我们比较峰值之间的最大差异,并使用该倾斜角度旋转图像以校正倾斜。
原来的->
已更正
倾斜角度:-2
import cv2
import numpy as np
from scipy.ndimage import interpolation as inter
def correct_skew(image, delta=1, limit=5):
def determine_score(arr, angle):
data = inter.rotate(arr, angle, reshape=False, order=0)
histogram = np.sum(data, axis=1, dtype=float)
score = np.sum((histogram[1:] - histogram[:-1]) ** 2, dtype=float)
return histogram, score
gray = cv2.cvtColor(image, cv2.COLOR_BGR2GRAY)
thresh = cv2.threshold(gray, 0, 255, cv2.THRESH_BINARY_INV + cv2.THRESH_OTSU)[1]
scores = []
angles = np.arange(-limit, limit + delta, delta)
for angle in angles:
histogram, score = determine_score(thresh, angle)
scores.append(score)
best_angle = angles[scores.index(max(scores))]
(h, w) = image.shape[:2]
center = (w // 2, h // 2)
M = cv2.getRotationMatrix2D(center, best_angle, 1.0)
corrected = cv2.warpAffine(image, M, (w, h), flags=cv2.INTER_CUBIC, \
borderMode=cv2.BORDER_REPLICATE)
return best_angle, corrected
if __name__ == '__main__':
image = cv2.imread('1.png')
angle, corrected = correct_skew(image)
print('Skew angle:', angle)
cv2.imshow('corrected', corrected)
cv2.waitKey()
Note:您可能需要调整delta
or limit
值取决于图像。这delta
value 控制迭代步长,它将迭代直到limit
它控制最大角度。这种方法很简单,通过迭代检查每个角度 +delta
目前仅适用于纠正 +/- 5 度范围内的倾斜。如果需要以更大的角度进行校正,请调整limit
价值。对于处理倾斜的另一种方法,看看这个替代方法 https://stackoverflow.com/questions/57713358/how-to-rotate-skewed-fingerprint-image-to-vertical-upright-position.