NID 文档扫描仪仅扫描所需的矩形

Question

我只想使用 python 从图像中裁剪出内部白色矩形。我用

findContours

尝试过，但由于边缘不清楚，因此没有显示任何更好的输出。这个怎么做。有谁能够帮助我。我是新来的。

import cv2 
import numpy as np 
 
# Load the image 
image = cv2.imread("doc.jpg") 
 
# Convert to grayscale 
gray = cv2.cvtColor(image, cv2.COLOR_BGR2GRAY) 
 
# Apply binary thresholding 
_, thresholded = cv2.threshold(gray, 128, 255, cv2.THRESH_BINARY) 

cv2.imshow("thresholded", thresholded) 

 
# Find contours 
contours, _ = cv2.findContours(thresholded, cv2.RETR_EXTERNAL, cv2.CHAIN_APPROX_SIMPLE) 
 
# Filter contours 
rects = [] 
for contour in contours: 
    # Approximate the contour to a polygon 
    polygon = cv2.approxPolyDP(contour, 0.01 * cv2.arcLength(contour, True), True) 
 
    # Check if the polygon has 4 sides and the aspect ratio is close to 1 
    if len(polygon) == 4 and abs(1 - cv2.contourArea(polygon) / (cv2.boundingRect(polygon)[2] * cv2.boundingRect(polygon)[3])) < 0.1: 
        rects.append(polygon) 
 
# Draw rectangles 
for rect in rects: 
    cv2.drawContours(image, [rect], 0, (0, 255, 0), 2) 
 
# Show the result 
cv2.imshow("Rectangles", image) 
cv2.waitKey(0) 
cv2.destroyAllWindows()

我尝试过这个但没有成功。

Answer 1

我只想使用以下命令从图像中裁剪内部白色矩形 蟒蛇。

可以通过使用鼠标事件绑定来解决该问题。

只需根据需要绘制一个矩形，然后按 Enter 键即可。

片段：

import cv2
import numpy as np

cropping = False

x_start, y_start, x_end, y_end = 0, 0, 0, 0

image = cv2.imread('driver_licence.jpg')
oriImage = image.copy()


def mouse_crop(event, x, y, flags, param):
    # grab references to the global variables
    global x_start, y_start, x_end, y_end, cropping

    # if the left mouse button was DOWN, start RECORDING
    # (x, y) coordinates and indicate that cropping is being
    if event == cv2.EVENT_LBUTTONDOWN:
        x_start, y_start, x_end, y_end = x, y, x, y
        cropping = True

    # Mouse is Moving
    elif event == cv2.EVENT_MOUSEMOVE:
        if cropping == True:
            x_end, y_end = x, y

    # if the left mouse button was released
    elif event == cv2.EVENT_LBUTTONUP:
        # record the ending (x, y) coordinates
        x_end, y_end = x, y
        cropping = False # cropping is finished

        refPoint = [(x_start, y_start), (x_end, y_end)]

        if len(refPoint) == 2: #when two points were found
            roi = oriImage[refPoint[0][1]:refPoint[1][1], refPoint[0][0]:refPoint[1][0]]
            cv2.imshow("Cropped", roi)
            cv2.imwrite('crop.jpg', roi)

cv2.namedWindow("image")
cv2.setMouseCallback("image", mouse_crop)

while True:

    i = image.copy()

    if not cropping:
        cv2.imshow("image", image)

    elif cropping:
        cv2.rectangle(i, (x_start, y_start), (x_end, y_end), (255, 0, 0), 2)       
        cv2.imshow("image", i)

    cv2.waitKey(1)


cv2.destroyAllWindows()