2014-10-12 15:50 10422人阅读 评论(0) 收藏 举报
python （1）
computer vision （5）
Conversions between Various Formats
Convert between Python tuple and lista = (1, 2) # a is a tuple b = list(a) # b is a list c = tuple(b) # c is a tuple Convert between Python tuple, list and NumPy 1D array a = (1, 2) # a is a tuple b = np.array(a) # b is an numpy array c = tuple(b) # c is a tuple a = [1, 2] # a is a python array b = np.array(a) # b is a numpy array c = list(b) # c is a python list Convert between NumPy 2D array and NumPy matrixa = numpy.ndarray([2,3]) # create 2x3 arraym1 = numpy.asmatrix(a) # does not create new matrix, m1 refers to the same memory as a m2 = numpy.matrix(a) # creates new matrix and copies content b1 = numpy.asarray(m2) # does not create array, b1 refers to the same memory as m2b2 = numpy.array(m2) # creates new array and copies content
Read/Write Images with OpenCVimage = cv.LoadImage(“ponzo.jpg”)cv.SaveImage(“out.png”, image)Read/Write Images with PILimage = Image.open(“ponzo.jpg”)image.save(“out.jpg”)Read/Write Images with PyOpenCV****mat = pyopencv.imread(“ponzo.jpg”)pyopencv.imwrite(“out.png”, mat)
Convert between OpenCV image and PIL image****# color image cimg = cv.LoadImage("ponzo.jpg", cv.CV_LOAD_IMAGE_COLOR) # cimg is a OpenCV imagepimg = Image.fromstring("RGB", cv.GetSize(cimg), cimg.tostring()) # pimg is a PIL image cimg2 = cv.CreateImageHeader(pimg.size, cv.IPL_DEPTH_8U, 3) # cimg2 is a OpenCV image cv.SetData(cimg2, pimg.tostring())Note: OpenCV stores color image in BGR format. So, the converted PIL image is also in BGR-format. The standard PIL image is stored in RGB format. # gray image cimg = cv.LoadImage("ponzo.jpg", cv.CV_LOAD_IMAGE_GRAYSCALE) # cimg is a OpenCV image pimg = Image.fromstring("L", cv.GetSize(cimg), cimg.tostring()) # pimg is a PIL image cimg2 = cv.CreateImageHeader(pimg.size, cv.IPL_DEPTH_8U, 1) # cimg2 is a OpenCV imagecv.SetData(cimg2, pimg.tostring())
Convert between PIL image and NumPy ndarrayimage = Image.open(“ponzo.jpg”) # image is a PIL image array = numpy.array(image) # array is a numpy array image2 = Image.fromarray(array) # image2 is a PIL image Convert between PIL image and PyOpenCV matriximage = Image.open(“ponzo.jpg”) # image is a PIL imagemat = pyopencv.Mat.from_pil_image(image) # mat is a PyOpenCV matrix image2 = mat.to_pil_image() # image2 is a PIL image
Convert between OpenCV image and NumPy ndarraycimg = cv.LoadImage("ponzo.jpg", cv.CV_LOAD_IMAGE_COLOR) # cimg is a OpenCV image pimg = Image.fromstring("RGB", cv.GetSize(cimg), cimg.tostring()) # pimg is a PIL image array = numpy.array(pimg) # array is a numpy array pimg2 = cv.fromarray(array) # pimg2 is a OpenCV image