如何使用OpenCV旋转视频流中的所有帧?我尝试了类似问题提供的代码,但它似乎无法与返回cv.RetrieveFrame的Iplimage图像对象一起使用。
这是我目前拥有的代码:
import cv, cv2
import numpy as np
def rotateImage(image, angle):
if hasattr(image, 'shape'):
image_center = tuple(np.array(image.shape)/2)
shape = image.shape
elif hasattr(image, 'width') and hasattr(image, 'height'):
image_center = (image.width/2, image.height/2)
shape = np.array((image.width, image.height))
else:
raise Exception, 'Unable to acquire dimensions of image for type %s.' % (type(image),)
rot_mat = cv2.getRotationMatrix2D(image_center, angle,1.0)
result = cv2.warpAffine(image, rot_mat, shape, flags=cv2.INTER_LINEAR)
return result
cap = cv.CaptureFromCAM(cam_index)
#cap = cv.CaptureFromFile(path)
fps = 24
width = int(cv.GetCaptureProperty(cap, cv.CV_CAP_PROP_FRAME_WIDTH))
height = int(cv.GetCaptureProperty(cap, cv.CV_CAP_PROP_FRAME_HEIGHT))
fourcc = cv.CV_FOURCC('P','I','M','1') #is a MPEG-1 codec
writer = cv.CreateVideoWriter('out.avi', fourcc, fps, (width, height), 1)
max_i = 90
for i in xrange(max_i):
print i,max_i
cv.GrabFrame(cap)
frame = cv.RetrieveFrame(cap)
frame = rotateImage(frame, 180)
cv.WriteFrame(writer, frame)
但这只会产生错误:
File "test.py", line 43, in <module>
frame = rotateImage(frame, 180)
File "test_record_room.py", line 26, in rotateImage
result = cv2.warpAffine(image, rot_mat, shape, flags=cv2.INTER_LINEAR)
TypeError: <unknown> is not a numpy array
据推测,这是因为warpAffine需要一个CvMat而不是Iplimage。根据C++ cheatsheet,在两者之间进行转换很简单,但我找不到有关在Python中进行等效操作的文档。如何在Python中将Iplimage转换为Mat?