Python OpenCV - 使用实时摄像头帧作为输入进行模板匹配

Question

我之前在Android上尝试过OpenCV，现在我又开始使用OpenCV 2和Python 2。到目前为止，我已经能够使用它来获取实时摄像头数据，并且在一个单独的项目中，我已经能够实现模板匹配，其中我会给出一个父图像和一个存在于父图像中的小图像，并匹配父图像中的子图像，然后输出另一张图片，在匹配的图像上画一个红色的矩形。

下面是模板匹配的代码。这并不特别，与OpenCV网站上的代码相同：

import cv2
import numpy as np
from matplotlib import pyplot as plt
img_rgb = cv2.imread('mario.jpg')
img_gray = cv2.cvtColor(img_rgb, cv2.COLOR_BGR2GRAY)
template = cv2.imread('mario_coin.png',0)
w, h = template.shape[::-1]
res = cv2.matchTemplate(img_gray,template,cv2.TM_CCOEFF_NORMED)
threshold = 0.8
loc = np.where( res >= threshold)
for pt in zip(*loc[::-1]):
    cv2.rectangle(img_rgb, pt, (pt[0] + w, pt[1] + h), (0,0,255), 2)
cv2.imwrite('res.png',img_rgb)

关于我的现场摄像头反馈代码，我有以下内容：

# import the necessary packages
from picamera.array import PiRGBArray
from picamera import PiCamera
import time
import cv2

# initialize the camera and grab a reference to the raw camera capture
camera = PiCamera()
camera.resolution = (640, 480)
camera.framerate = 32
rawCapture = PiRGBArray(camera, size=(640, 480))

# allow the camera to warmup
time.sleep(0.1)

# capture frames from the camera
for frame in camera.capture_continuous(rawCapture, format="bgr", use_video_port=True):
    # grab the raw NumPy array representing the image, then initialize the timestamp
    # and occupied/unoccupied text
    image = frame.array

    # show the frame
    cv2.imshow("Frame", image)
    key = cv2.waitKey(1) & 0xFF

    # clear the stream in preparation for the next frame
    rawCapture.truncate(0)

    # if the `q` key was pressed, break from the loop
    if key == ord("q"):
        break

到目前为止，这两个代码都很好地独立运行。我尝试的是将模板匹配代码插入在摄像头流代码显示任何内容之前的部分。

下面是我想出的代码：

from picamera.array import PiRGBArray
from picamera import PiCamera
from matplotlib import pyplot as plt

import time
import cv2
import numpy as np


# initialize the camera and grab a reference to the raw camera capture
camera = PiCamera()
camera.resolution = (640, 480)
camera.framerate = 32
rawCapture = PiRGBArray(camera, size=(640, 480))

template = cv2.imread('mario_coin.png', 0)


# allow the camera to warmup
time.sleep(0.1)

# capture frames from the camera
for frame in camera.capture_continuous(rawCapture, format="bgr",
                                       use_video_port=True):
    # grab the raw NumPy array representing the image,
    # then initialize the timestamp
    # and occupied/unoccupied text
    image = frame.array

    # we do something here
    # we get the image or something then run some matching
    # if we get a match, we draw a square on it or something
##    img_rbg = cv2.imread('mario.jpg')
    img_rbg = image

##    img_gray = cv2.cvtColor(img_rgb, cv2.COLOR_RGB2GRAY)
    img_gray = cv2.cvtColor(image, cv2.COLOR_RGB2GRAY)



    w, h = template.shape[::-1]

    res = cv2.matchTemplate(img_gray, template, cv2.TM_CCOEFF_NORMED)

    threshold = 0.8

    loc = np.where(res >= threshold)

    for pt in zip(*loc[::-1]):
##        cv2.rectangle(img_rbg, pt, (pt[0] + w, pt[1] + h),
##                      (0,0,255), 2)
        cv2.rectangle(image, pt, (pt[0] + w, pt[1] + h),
                      (0,0,255), 2)

##    image = img_rgb


    # show the frame
    cv2.imshow("Frame", image)
    key = cv2.waitKey(1) & 0xFF

    # clear the stream in preparation for the next frame
    rawCapture.truncate(0)

    # if the `q` key was pressed, break from the loop
    if key == ord("q"):
        break

我要做的是，不使用cv2.imread(sample.png)，而是使用来自摄像头的图像输入，并将其用于之前的模板匹配算法。但是摄像头只打开了一秒钟（由灯光指示），然后关闭并停止程序。我真的不知道发生了什么。有人知道如何使用实时摄像头作为模板匹配的输入吗？我正在使用带有v1.3相机的Raspberry Pi 2。

- Razgriz

Answer 1

我实际上已经解决了它。我忘记了我在这里发布了一个问题。

from picamera.array import PiRGBArray
from picamera import PiCamera
from matplotlib import pyplot as plt

import time
import cv2
import numpy as np


# initialize the camera and grab a reference to the raw camera capture
camera = PiCamera()
camera.resolution = (640, 480)
camera.framerate = 32
rawCapture = PiRGBArray(camera, size=(640, 480))

template = cv2.imread('mario_coin.png', 0)


# allow the camera to warmup
time.sleep(0.1)

# capture frames from the camera
for frame in camera.capture_continuous(rawCapture, format="bgr",
                                       use_video_port=True):
    # grab the raw NumPy array representing the image,
    # then initialize the timestamp
    # and occupied/unoccupied text
    image = frame.array

    # we do something here
    # we get the image or something then run some matching
    # if we get a match, we draw a square on it or something
    img_rbg = image

    img_gray = cv2.cvtColor(img_rgb, cv2.COLOR_BGR2GRAY)


    template = cv2.imread("mario_coin.png", 0)
    w, h = template.shape[::-1]

    res = cv2.matchTemplate(img_gray, template, cv2.TM_CCOEFF_NORMED)

    threshold = 0.8

    loc = np.where(res >= threshold)

    for pt in zip(*loc[::-1]):
        cv2.rectangle(image, (pt[1]. pt[0]), (pt[1] + w, pt[0] + h),
                      (0,0,255), 2)

    # show the frame
    cv2.imshow("Frame", img_rbg)
    key = cv2.waitKey(1) & 0xFF

    # clear the stream in preparation for the next frame
    rawCapture.truncate(0)

    # if the `q` key was pressed, break from the loop
    if key == ord("q"):
        break

- Razgriz

Answer 2

我之前也遇到过同样的问题，问题在于变量res。当你第一次启动脚本时，res是空的，所以在np.where函数中比较一个空变量是行不通的。

因此，你应该添加一个：

• 条件（如果 res :）
• 或者一个 异常（尝试：… except:）

由于我现在没有我的树莓派，所以这里是使用笔记本摄像头和OpenCV的相同示例：

import cv2
import numpy as np

name = 'find.png' 
template = cv2.imread(name,0)
face_w, face_h = template.shape[::-1]

cv2.namedWindow('image')

cap = cv2.VideoCapture(0)

threshold = 1
ret = True

while ret :
    ret, img = cap.read()

    #flip the image  ! optional 
    img = cv2.flip(img,1)

    img_gray = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)

    res = cv2.matchTemplate(img_gray,template,cv2.TM_CCOEFF_NORMED)

    if len(res):
        location = np.where( res >= threshold)
        for i in zip(*location[::-1]):
            #puting  rectangle on recognized erea 
            cv2.rectangle(img, pt, (pt[0] + face_w, pt[1] + face_h), (0,0,255), 2)

    cv2.imshow('image',img)
    k = cv2.waitKey(5) & 0xFF
    if k == 27:
        break
cv2.destroyAllWindows()

- MED-ELOMARI