如何在 Open CV Python 中缩放我的网络摄像头？

Question

I want my webcam to be zoomed in open cv python and I don't know how. Can anyone help me with my problem?

import cv2
video = cv2.VideoCapture(0)
while True:
    check, frame = video.read()
    cv2.imshow('Video', frame)
    key = cv2.waitKey(1)
    if key == 27:
        break
  video.release()
  cv2.destroyAllWindows

Answer 1

You can use this solution. It makes the job -> croping + zoom + array up and array down.

import cv2

        def show_webcam(mirror=False):
            scale=10

            cam = cv2.VideoCapture(0)
            while True:
                ret_val, image = cam.read()
                if mirror: 
                    image = cv2.flip(image, 1)


                #get the webcam size
                height, width, channels = image.shape

                #prepare the crop
                 centerX,centerY=int(height/2),int(width/2)
                radiusX,radiusY= int(scale*height/100),int(scale*width/100)

                minX,maxX=centerX-radiusX,centerX+radiusX
                minY,maxY=centerY-radiusY,centerY+radiusY

                cropped = image[minX:maxX, minY:maxY]
                resized_cropped = cv2.resize(cropped, (width, height)) 

                cv2.imshow('my webcam', resized_cropped)
                if cv2.waitKey(1) == 27: 
                    break  # esc to quit

                #add + or - 5 % to zoom

                if cv2.waitKey(1) == 0: 
                    scale += 5  # +5

                if cv2.waitKey(1) == 1: 
                    scale = 5  # +5

            cv2.destroyAllWindows()


        def main():
            show_webcam(mirror=True)


        if __name__ == '__main__':
            main()

Answer 2

Zooming is simply increasing image size . Just increase image size by converting frame to image using PIL and then resize function. Sample code

    import tkinter
    import cv2
    from PIL import Image,ImageTk


    root = tkinter.Tk()

    root.geometry("1000x500+200+0")
    w = 1000
    h = 630

    capture = tkinter.Canvas(root, bd=2, bg="blue", height=h, width=w)
    capture.grid(column = 0, row = 0)
    video = None
    frame = None
    img=None
    show=None
    begin = False
    def start_capture(event):
        global begin,frame,img,root,show,capture,video    
        video = cv2.VideoCapture(0)
        begin = True
        while begin:
            check, frame = video.read()

            img = Image.fromarray(frame)
            w,h = img.size
            img = img.resize((w*2,h*2))
            show = ImageTk.PhotoImage(img)
            capture.create_image(0,0,anchor=tkinter.NW,image=show)
            root.update()

    def stop_capture(event):
        global video,begin
        begin = False
        video.release()

    start = tkinter.Button(root, text='Start')
    start.grid(column = 0, row = 2)
    start.bind('<Button-1>', start_capture)  
    stop = tkinter.Button(root, text='Stop')
    stop.grid(column = 1, row = 2)
    stop.bind('<Button-1>', stop_capture)  

    root.mainloop()

Answer 3

I am not sure if this is useful now to add this point. (Hope this helps for all the noobs in opencv at least)

I suffered a lot at this: cropped = image[minX:maxX, minY:maxY] Crop was somehow out of the interested area.

After researching a lot, I found out that the problem was with the syntax. Actually it should have been : cropped = image[minY:maxY , minX:maxX] because openCV crop syntax should be like this?..

Anyways, thanks to Amara BOUDIB & JDS for the sample codes!