opencv fun: 蓝线特效

简介：开始是在b站上看到很多蓝线特效视频很搞笑，在手机应用商店里面没找到类似的软件，所以就手动写一个在笔记本上玩玩。下面的代码很短，麻雀虽小五脏俱全呐。

1. 效果：

   
   蓝线特效.gif

2. 代码：

import cv2
import numpy as np

def blueLineUpToDown(speed=3):
    cap = cv2.VideoCapture(0)
    ret,frame = cap.read()
    finalImage = np.zeros(frame.shape,np.uint8)
    line = 0

    while (1):
        ret,frame = cap.read()
        line += speed
        if line >= finalImage.shape[0]:
            break

        finalImage[line:,:] = frame[line:,:]
        cv2.line(finalImage,(0,line+2*speed),(finalImage.shape[1],line+2*speed),(0,255,0),2)
        cv2.imshow("img",finalImage)
        #cv2.imshow("frame",frame)
        if cv2.waitKey(1) & 0xFF == ord("q"):
            break

    cap.release()
    cv2.destroyAllWindows()
    cv2.imshow("final",finalImage)
    #cv2.imwrite("./img.png",finalImage)
    cv2.waitKey(0)
    cv2.destroyWindow("final")
    
def blueLineLeftToRight(speed=3):
    cap = cv2.VideoCapture(0)
    ret,frame = cap.read()
    finalImage = np.zeros(frame.shape,np.uint8)
    line = 0

    while (1):
        ret,frame = cap.read()
        line += speed
        if line >= finalImage.shape[1]:
            break

        finalImage[:,line:] = frame[:,line:]
        cv2.line(finalImage,(line+2*speed,0),(line+2*speed,finalImage.shape[1]),(0,255,0),2)
        cv2.imshow("img",finalImage)
        #cv2.imshow("frame",frame)
        if cv2.waitKey(1) & 0xFF == ord("q"):
            break

    cap.release()
    cv2.destroyAllWindows()
    cv2.imshow("final",finalImage)
    #cv2.imwrite("./img.png",finalImage)
    cv2.waitKey(0)
    cv2.destroyWindow("final")
    
if __name__ == "__main__":
    speed = 1 
    mode = 1
    if mode ==0:
        blueLineUpToDown(speed) 
    else:
        blueLineLeftToRight(speed)