[英]How can I select ROI in a separate image in opencv-python?
我正在使用python 2.7.13和opencv 3.4.0。 我有一个有2个绿点的视频流。 我正在使用颜色检测来跟踪它们。 我需要在两个单独的图像中选择两个ROI(感兴趣的区域),每个ROI包含一个点,以进行进一步处理。 我写了一个程序来检测它们并创建ROI,但是问题是它只选择一个区域,而有两个点。 此外,它给了我错误:“第47行,在cv2.imshow(”area1“,area1)NameError:名称'area1'未定义”
但是如果我用img = cv2.imread(“image.jpg”)替换img = frame.array行,那么它可以工作,但只能用图片。 这里程序如何运作
import cv2
import numpy as np
from picamera.array import PiRGBArray
from picamera import PiCamera
import time
import sys
lowerBound=np.array([33,80,40])
upperBound=np.array([102,255,255]) #ranges for green color
camera = PiCamera()
camera.rotation = 180
camera.resolution = (320, 240)
camera.framerate = 30
font=cv2.FONT_HERSHEY_SIMPLEX
rawCapture = PiRGBArray(camera, size=(320, 240))
time.sleep(0.1)
kernelOpen=np.ones((5,5))
kernelClose=np.ones((20,20))
for frame in camera.capture_continuous(rawCapture, format="bgr", use_video_port=True): # capture frames from the camera
img = frame.array #works only if I change this with img =cv2.imread("image.jpg")
imgHSV= cv2.cvtColor(img,cv2.COLOR_BGR2HSV)
mask=cv2.inRange(imgHSV,lowerBound,upperBound)
maskOpen=cv2.morphologyEx(mask,cv2.MORPH_OPEN,kernelOpen)
maskClose=cv2.morphologyEx(maskOpen,cv2.MORPH_CLOSE,kernelClose) #apply morphology for greater accuracy
maskFinal=maskClose
_, conts, _=cv2.findContours(maskFinal.copy(),cv2.RETR_EXTERNAL,cv2.CHAIN_APPROX_NONE)
for i in range(len(conts)):
x,y,w,h=cv2.boundingRect(conts[i])
area1=img[y:y+h, x:x+w] #selecting my ROI
cv2.rectangle(img,(x,y),(x+w,y+h),(0,0,255), 2)
cv2.imshow("maskClose",maskClose)
cv2.imshow("maskOpen",maskOpen)
cv2.imshow("mask",mask)
cv2.imshow("cam",img)
cv2.imshow ("area1",area1) #Showing my ROI
key = cv2.waitKey(1) & 0xFF
rawCapture.truncate(0)
if key == ord("q"):
break
在for循环中,您可以设置/覆盖area1
,因此输出将始终只是一个图像。 您可以通过将imshow()移到for循环中来轻松解决此问题。
在代码顶部添加:
prevNrOfContours = 0
使用以下代码更改帧循环:
# create a window for each roi
nrOfContours = len(conts)
for i in range(nrOfContours):
x,y,w,h=cv2.boundingRect(conts[i])
area=img[y:y+h, x:x+w] #selecting my ROI
cv2.rectangle(img,(x,y),(x+w,y+h),(0,0,255), 2)
cv2.imshow("area" + str(i), area)
# if there are more open windows then roi's
# then close the windows that will not be refreshed
if prevNrOfContours > nrOfContours:
for i in range(nrOfContours, prevNrOfContours):
cv2.destroyWindow("area" + str(i))
# store the number of roi's in this frame, so it can
# be used in the next frame
prevNrOfContours = nrOfContours
编辑:扩展代码,删除不必要的打开的窗口
Edit2:仅选择2个最大轮廓:
# instantiate list
contour_list = []
for cnt in contours:
# get contour size
area = cv2.contourArea(cnt)
# add tuple of the contour and its size to the list
contour_list.append((cnt, area))
# sort list on size
sorted_list = sorted(contour_list, key=lambda x: x[1])
# create a window for the 2 largest contours
for i in range(-2,0):
x,y,w,h=cv2.boundingRect(sorted_list[i][0])
roi=img[y:y+h, x:x+w] #selecting my ROI
cv2.rectangle(img,(x,y),(x+w,y+h),(0,0,255), 2)
cv2.imshow("area" + str(i), roi)
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