如何将倾斜的指纹图像旋转到垂直直立位置

Question

我想将指纹图像从倾斜旋转到垂直中心

通过 python 和 opencv

我是新手

由此

对此

Answer 1

给定包含未知角度的旋转斑点的图像，可以使用此方法校正倾斜

检测图像中的斑点
计算旋转 blob 的角度
旋转图像以校正歪斜

为了检测图像中的斑点，我们转换为灰度和自适应阈值以获得二值图像

image = cv2.imread('1.jpg')
gray = cv2.cvtColor(image, cv2.COLOR_BGR2GRAY)
gray = 255 - gray
thresh = cv2.threshold(gray, 0, 255, cv2.THRESH_BINARY + cv2.THRESH_OTSU)[1]

接下来我们使用 cv2.minAreaRect() 计算旋转斑点的角度并计算倾斜角度

# Compute rotated bounding box
coords = np.column_stack(np.where(thresh > 0))
angle = cv2.minAreaRect(coords)[-1]

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

43.72697067260742

最后我们应用仿射变换来纠正偏斜

# Rotate image to deskew
(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)

这是结果

import cv2
import numpy as np

image = cv2.imread('1.jpg')
gray = cv2.cvtColor(image, cv2.COLOR_BGR2GRAY)
gray = 255 - gray
thresh = cv2.threshold(gray, 0, 255, cv2.THRESH_BINARY + cv2.THRESH_OTSU)[1]

# Compute rotated bounding box
coords = np.column_stack(np.where(thresh > 0))
angle = cv2.minAreaRect(coords)[-1]

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

# Rotate image to deskew
(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.imshow('thresh', thresh)
cv2.imshow('rotated', rotated)
cv2.waitKey()

如何将倾斜的指纹图像旋转到垂直直立位置

How to rotate skewed fingerprint image to vertical upright position

python

opencv

image

image-processing

rotation