如何使用光标在 OpenCV 中移动视频？

Question

我目前正在尝试实现一个功能，该功能允许我使用光标“抓取”视频并四处移动。我希望能够仅在按住并移动光标时移动视频。我已经定义了鼠标事件，捕获了光标的坐标，但我不知道如何编写函数来裁剪视频。

x1, x2, y1, y2 = 0, 0, 0, 0
mouse_down = False

def mouse_event_callback(event, x, y, flags, param):
    global x1, x2, y1, y2, mouse_down

    if event == cv2.EVENT_LBUTTONDOWN:
        x1, y1 = x, y
        mouse_down = True

    elif event == cv2.EVENT_MOUSEMOVE:
        if mouse_down:
            x2, y2 = x, y
            mouse_grab_video(x1, x2, y1, y2)

    elif event == cv2.EVENT_LBUTTONUP:
        mouse_down = False

def mouse_grab_video(x1, x2, y1, y2):
    ...

任何帮助将不胜感激！

Answer 1

您可以根据从鼠标事件获得的坐标直接裁剪图像。

#!/usr/bin/env python3
import argparse
import cv2
import numpy as np
from PIL import Image

drawing = False # true if mouse is pressed
ix,iy = -1,-1
refPt = []
img = ""
clone = ""
ROIRegion = []

# mouse callback function
def draw_rectangle(event,x,y,flags,param):
    global ix,iy,drawing,img,clone,refPt, ROIRegion
    if event == cv2.EVENT_LBUTTONDOWN:
        drawing = True
        ix,iy = x,y
        refPt = [(x, y)]
        ROIRegion.append(refPt)
        #clone = img.copy()

    elif event == cv2.EVENT_MOUSEMOVE:
        if drawing == True:
            img = clone.copy()
            cv2.rectangle(img,(ix,iy),(x,y),(0,255,0),3)
            a=x
            b=y
            if a != x | b != y:
                cv2.rectangle(img,(ix,iy),(x,y),(0,0,0),-1)

    elif event == cv2.EVENT_LBUTTONUP:
        drawing = False
        refPt.append((x,y))
        img = clone.copy()
        cv2.rectangle(img, (ix,iy),(x,y), (0, 255, 0), 2)


ap = argparse.ArgumentParser()
ap.add_argument("-i", "--image", required=True, help="Path to the image")
args = vars(ap.parse_args())
img = cv2.imread(args["image"])
img = np.array(img)
clone = img.copy()

cv2.namedWindow('image')
cv2.setMouseCallback('image',draw_rectangle)
while(1):
    cv2.imshow('image',img)

    k = cv2.waitKey(1) & 0xFF
    if k == ord("r"):
        del ROIRegion[-1]
        del refPt[-1]
        img = clone.copy()

    elif k == 27:
        break

#Crop image to ROI
for region in range(len(ROIRegion)):
    cv2.rectangle(img, ROIRegion[region][0],ROIRegion[region][1], (0, 255, 0), 2)
    roi = clone[ROIRegion[region][0][1]:ROIRegion[region][1][1], ROIRegion[region][0][0]:ROIRegion[region][1][0]]

对于缩放，您可以使用 EVENT_MOUSEWHEEL 来增加比例并根据比例调整图像大小。更新 imshow 以获取您缩放的最新图像。你可以参考这个link