捕获图像进行处理

Question

我将 Python 与 PIL 和 SciPy 结合使用。 我想从网络摄像头捕获图像，然后使用 numpy 和 Scipy 进一步处理它。有人可以帮我写代码吗？

这里是预定义图像“lena”的代码，但我希望使用我自己捕获的图像而不是“lena”图像。我对代码做了哪些更改？

from scipy import misc
lena = misc.lena()
lx, ly = lena.shape
import matplotlib.pyplot as plt
crop_lena = lena[lx / 4: - lx / 4, ly / 4: - ly / 4]
plt.imshow(crop_lena)

另一个例子

import scipy
from scipy import ndimage
import matplotlib.pyplot as plt
import numpy as np
l = scipy.misc.lena()
plt.figure(figsize=(10, 3.6))
plt.subplot(131)
plt.imshow(l, cmap=plt.cm.gray)
plt.show()

Answer 1

Video Capture by Markus Gritsch

我用过很多Video Capture by Markus Gritsch，这可能是做你想做的最简单和最快的方法。

from VideoCapture import Device
from numpy import *
from PIL import Image
cam = Device(devnum=0, showVideoWindow=0) #devnum=0 means you are using the device set in 0 position probably your webcam
blackimg= cam.getImage() #this return a PIL image but I don't know why the first is always black
#blackimag.show()#try to check if you want
image=cam.getImage() #this is a real image PIL image
imgarray = asarray(image) #convert the image into a matrix
#imgarrayfloat = imgarray.astype('float') # in many cases of processing you have to convert to a float matrix because can occur overflow (e.g. for average images summing  pixels values of 255 and 3 of two images and divide by 2 gives you 1/2 for imgarray and 258/2 for imgarrayfloat 
#recovertedimage=processedimage.astype ("uint8")#if you use the previous you have to reconvert to unit8. Note processedimage is the name of the variable of your image.

Python OpenCV: cv2 & cv

您也可以使用OpenCV 的 Python 绑定来完成此操作。至少有两种方法可以做到这一点。我发现 this 和 this 教程很有趣。

Video Capture

from cv2 import *
cam = VideoCapture(0)  #set the port of the camera as before
retval, image = cam.read() #return a True bolean and and the image if all go right
cam.release() #Closes video file or capturing device.

在这种情况下，您有一个 numpy.ndarray（不再有 PIL 图像），以便在 shell 中显示图像类型：

import matplotlib.pyplot as plt
plt.imshow(image)

CaptureFromCAM 的老方法

import cv2.cv as cv 
import numpy as np  
Capture = cv.CaptureFromCAM(0)
image = cv.QueryFrame(Capture) #here you have an IplImage
imgarray = np.asarray(image[:,:]) #this is the way I use to convert it to numpy array

你可以如上所示。

Answer 2

您可以使用 VideoCapture 库从 USB 摄像头获取图片。

from VideoCapture import Device

came = Device()
came.setResolution(320, 240)

img = cam.getImage()
...