如何使用Python通过网络摄像头捕获身份证尺寸的照片

Question

我有这几行代码，可以使用网络摄像头捕获图像，但图片的宽度和高度很大。这是我可以的方法吗 框架要小，以拍摄护照照片大小的图像。

我可以使用任何可用资源来实现这一目标。这就是我希望我的框架的样子，这样我就可以使用网络摄像头捕获从头到肩的图像。

附有示例图片

import cv2

key = cv2.waitKey(1)
webcam = cv2.VideoCapture(0)
while True:
    try:
        check, frame = webcam.read()
        print(check)  # prints true as long as the webcam is running
        print(frame)  # prints matrix values of each framecd
        cv2.imshow("Capturing", frame)
        key = cv2.waitKey(1)
        if key == ord('s'):
            cv2.imwrite(filename='saved_img.jpg', img=frame)
            webcam.release()
            img_new = cv2.imread('saved_img.jpg', cv2.IMREAD_UNCHANGED)
            img_new = cv2.imshow("Captured Image", img_new) # SHOWS THE IMAGE AFTER CAPTURING
            cv2.waitKey(1650)
            cv2.destroyAllWindows()
            print("captured images saved")

            break
        elif key == ord('q'):
            print("Turning off camera.")
            webcam.release()
            print("Camera off.")
            print("Program ended.")
            cv2.destroyAllWindows()
            break

    except(KeyboardInterrupt):
        print("Turning off camera.")
        webcam.release()
        print("Camera off.")
        print("Program ended.")
        cv2.destroyAllWindows()
        break

Answer 1

以下是如何使用 Python/PIL 裁剪为 2in x 2in。我们需要使用 PIL 来设置密度。我不相信 OpenCV 允许这样做。我假设你想在中心裁剪。如果没有，例如从顶部，请告诉我。但是，除非您有一个允许指定裁剪位置的交互式系统，否则您无法考虑每张图片，即框架中的人有多大。

输入（假设固定 480x640 纵向模式尺寸）：

import numpy as np
from PIL import Image

# read the input
img = Image.open('portrait.jpg')

# get dimensions (assume 480x640)
width, height = img.size

# for 2in x 2in printed result, we want to crop an aspect ratio of 1:1 in center
# so since the height will be larger than the width, we use the width for both dimensions
w2 = xcent = width//2
h2 = ycent = height//2
top = ycent - w2
left = xcent - w2
bottom = ycent + w2
right = xcent + w2

# crop input
crop = img.crop((left, top, right, bottom))

# get crop size
wd, ht = crop.size

# save image with density appropriate for 2in x 2in print
xprint = 2
yprint = 2
xdensity = wd//xprint
ydensity = ht//yprint
crop.save('portrait_2in_x_2in.jpg', dpi=(xdensity, ydensity))

# show cropped Image
crop.show()

裁剪结果：