Question

我正在尝试使用鼠标作为输入在Python中使用Opencv绘制矩形。我从opencv文档中创建了这段代码。绘制矩形时有问题，当您尝试从起点矩形拖动时一直绘制到终点。就像我在图像中展示的那样。

如何绘制干净的未填充矩形？在那里我可以看到绘制一个实际的矩形。就像我们在Paint中做的那样

import cv2
import numpy as np

drawing = False 
ix,iy = -1,-1

def draw_rect(event,x,y,flags,param):
global ix,iy,drawing,mode

if event == cv2.EVENT_LBUTTONDOWN:
    drawing = True
    ix,iy = x,y

elif event == cv2.EVENT_MOUSEMOVE:
    if drawing == True:
            cv2.rectangle(img,(ix,iy),(x,y),(0,255,0),1)


elif event == cv2.EVENT_LBUTTONUP:
    drawing = False
    cv2.rectangle(img,(ix,iy),(x,y),(0,255,0),1)



img = np.zeros((512,512,3), np.uint8)
cv2.namedWindow('image')
cv2.setMouseCallback('image',draw_rect)

while(1):
cv2.imshow('image',img)
k = cv2.waitKey(1) & 0xFF
if k == 27:
    break

cv2.destroyAllWindows()

谁能告诉我为什么会这样？有什么解决方案??

Answer 1

在event == cv2.EVENT_MOUSEMOVE期间移动鼠标时，您还会同时绘制recatngle cv2.rectangle(img,(ix,iy),(x,y),(0,255,0),1)。

尝试以下代码。

import cv2
import numpy as np

drawing = False # true if mouse is pressed
mode = True # if True, draw rectangle.
ix,iy = -1,-1

# mouse callback function
def draw_circle(event,x,y,flags,param):
  global ix,iy,drawing,mode

  if event == cv2.EVENT_LBUTTONDOWN:
      drawing = True
      ix,iy = x,y

  elif event == cv2.EVENT_MOUSEMOVE:
    if drawing == True:
        if mode == True:
            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)
        else:
            cv2.circle(img,(x,y),5,(0,0,255),-1)

  elif event == cv2.EVENT_LBUTTONUP:
    drawing = False
    if mode == True:
        cv2.rectangle(img,(ix,iy),(x,y),(0,255,0),2)

    else:
        cv2.circle(img,(x,y),5,(0,0,255),-1)

img = np.zeros((512,512,3), np.uint8)
cv2.namedWindow('image')
cv2.setMouseCallback('image',draw_circle)

while(1):
 cv2.imshow('image',img)
 k = cv2.waitKey(1) & 0xFF
 if k == ord('m'):
    mode = not mode
 elif k == 27:
    break

cv2.destroyAllWindows()

希望它能解决你的问题。欢呼声。

预期产出：

更新

上面的代码只能用于黑色背景图像。但我们可以在任何图像上绘制矩形 -

尝试以下代码。

# import the necessary packages
import cv2
import argparse

# now let's initialize the list of reference point
ref_point = []

def shape_selection(event, x, y, flags, param):
    # grab references to the global variables
    global ref_point, crop

    # if the left mouse button was clicked, record the starting
    # (x, y) coordinates and indicate that cropping is being performed
    if event == cv2.EVENT_LBUTTONDOWN:
        ref_point = [(x, y)]

    # check to see if the left mouse button was released
    elif event == cv2.EVENT_LBUTTONUP:
        # record the ending (x, y) coordinates and indicate that
        # the cropping operation is finished
        ref_point.append((x, y))

        # draw a rectangle around the region of interest
        cv2.rectangle(image, ref_point[0], ref_point[1], (0, 255, 0), 2)
        cv2.imshow("image", image)


# construct the argument parser and parse the arguments
ap = argparse.ArgumentParser()
ap.add_argument("-i", "--image", required=True, help="Path to the image")
args = vars(ap.parse_args())

# load the image, clone it, and setup the mouse callback function
image = cv2.imread(args["image"])
clone = image.copy()
cv2.namedWindow("image")
cv2.setMouseCallback("image", shape_selection)


# keep looping until the 'q' key is pressed
while True:
    # display the image and wait for a keypress
    cv2.imshow("image", image)
    key = cv2.waitKey(1) & 0xFF

    # press 'r' to reset the window
    if key == ord("r"):
        image = clone.copy()

    # if the 'c' key is pressed, break from the loop
    elif key == ord("c"):
        break

# close all open windows
cv2.destroyAllWindows()

将文件另存为capture_events.py并进行测试，我们选择了位于同一目录的演示图片。现在按照 -

运行代码

python capture_events.py --image demo.jpg

预期产出：

如果出于某种原因我们想要重新选择图片的任何部分，我们只需按下＆＃39; r＆＃39;摆脱糟糕的选择尝试一个新的。

希望，它会提供更多帮助。检查此gist，您可以在此实现更多功能。欢呼声。

Answer 2

您可以将鼠标事件更改为类似的内容

elif event == cv2.EVENT_MOUSEMOVE:
if drawing==True:
    copy = image.copy()
    cv2.rectangle(copy,(ix,iy),(x,y),(0,255,0),1)
    cv2.imshow("image", copy)

脚本将基于当前的x和y创建带有矩形的图像副本，并显示实时效果

Answer 3

我设法使用副本解决了这个问题。现在，仅需一个imshow（）更新即可使用。使用全局变量可能不是最好的方法。

import cv2 as cv


drawing = False
ix, iy = -1, -1


def draw_markers(event, x, y, flags, param):
    global ix, iy, drawing, frame, frame_copy
    if flags == cv.EVENT_FLAG_ALTKEY + cv.EVENT_FLAG_LBUTTON:
        if event == cv.EVENT_LBUTTONDOWN:
            print("Alt + lmouse down")
            drawing = True
            ix, iy = x, y
            frame_copy = frame.copy()
        elif event == cv.EVENT_MOUSEMOVE:
            if drawing:
                frame = cv.rectangle(
                    frame_copy.copy(), (ix, iy), (x, y), (0, 255, 0), 2)
        elif event == cv.EVENT_LBUTTONUP:
            print("Alt + lmouse up")
            drawing = False
            cv.rectangle(frame, (ix, iy), (x, y), (0, 255, 0), 2)

    elif event == cv.EVENT_LBUTTONUP:
        print("Draw crosshair")
        cv.drawMarker(frame, (x, y), (255, 0, 0), 0, 16, 2, 8)


cap = cv.VideoCapture('video.avi')
cap.set(cv.CAP_PROP_POS_FRAMES, 1)
ret, frame = cap.read()
frame_copy = frame.copy()
cv.namedWindow('frame')
cv.setMouseCallback('frame', draw_markers)

while(True):
    cv.imshow('frame', frame)
    if cv.waitKey(1) & 0xFF == ord('q'):
        break

cap.release()
cv.destroyAllWindows()

Answer 4

基于先前的答案，我设法创建了一个脚本，可以在图像上绘制矩形和任意大小的圆。在按住鼠标左键的同时四处移动鼠标会更新矩形。通过分别按r或t，圆会变大或变小。按“ m”在模式之间切换。按“ x”重置图像（删除您绘制的所有内容）。这是代码，显然可以进行更多优化，我将继续努力。

import cv2
import numpy as np
drawing = False # true if mouse is pressed
mode = True # if True, draw rectangle. Press 'm' to toggle to curve
ix,iy = -1,-1
x_, y_ = 0,0
r = 15 #circle radius
# mouse callback function
def draw_shape(event,x,y,flags,param):
    print(event)
    global ix,iy,drawing,mode,x_,y_, r

    if event == cv2.EVENT_LBUTTONDOWN:
        print('inside mouse lbutton event....')
        drawing = True
        ix,iy = x,y
        x_,y_ = x,y
    elif event == cv2.EVENT_MOUSEMOVE and drawing:
        copy = img.copy()
        x_,y_ = x,y
        if mode:
            cv2.rectangle(copy,(ix,iy),(x_,y_),(0,255,0),1)
            cv2.imshow("image", copy)
        else:
            cv2.circle(copy,(x,y),r,(0,0,255),1)
            cv2.imshow('image', copy)
    #
    elif event == cv2.EVENT_LBUTTONUP:
        print('inside mouse button up event')
        drawing = False
        if mode:
            cv2.rectangle(img,(ix,iy),(x,y),(0,255,0),1)
        else:
            cv2.circle(img,(x,y),r,(0,0,255),1)


img = np.zeros((512,512,3), np.uint8)
temp_img = np.copy(img)
cv2.namedWindow('image')
cv2.setMouseCallback('image',draw_shape)
while(1):
    # print('inside while loop...')
    cv2.imshow('image',img)
    if not cv2.EVENT_MOUSEMOVE:
        copy = img.copy()
        # print('x_: , y_ : '.format(x_,y_))
        print(x_)
        if mode == True:
            cv2.rectangle(copy,(ix,iy),(x_,y_),(0,255,0),1)
            cv2.imshow('image',copy)
        else:
            cv2.circle(copy,(x_,y_),r,(0,0,255),1)
            cv2.imshow('image',copy)
    k = cv2.waitKey(1) & 0xFF
    if k == ord('m'): #toggle between circle and rectangle
        mode = not mode
        x_,y_ = -10,-10
        ix,iy = -10,-10
    elif k == ord('r') and not mode: #make circle bigger
        r += 1
    elif k == ord('t') and not mode: #make circle smaller
        if r <=2:
            r = 1
        else:
            r -= 1
    elif k == ord('x'): #resets the image (removes circles and rectangles)
        img = np.copy(temp_img)
        x_,y_ = -10,-10
        ix,iy = -10,-10
    elif k == 27:
        break
cv2.destroyAllWindows()

在openCV python中绘制矩形

4 个答案:

更新