OpenCV Python save jpg specifying quality; gives SystemError
I just installed the newest OpenCV 2.4 on windows 7 (32bit)/ Python 2.7.3,
but I still get the same error I got using the beta version:
>>> import cv2 >>> a = cv2.imread(r"DMap.jpg") >>> a.shape (1080, 1920, 3) >>> cv2.imwrite('img_CV2_90.jpg', a, [cv2.IMWRITE_JPEG_QUALITY, 90]) Traceback (most recent call last): File "<input>", line 1, in <module> SystemError: error return without exception set Any ideas ? Using tuple instead of list, or adding a trailing 0 to the sequence does not help – same error.
Thanks – Sebastian Haase
It is probably due to some wrong wrapping of the imwrite() parameters from Python to C, cv2.IMWRITE_JPEG_QUALITY (which is of type “long”), and causes some weird problems. You should try to convert this constant to “int” type:
cv2.imwrite('img_CV2_90.jpg', a, [int(cv2.IMWRITE_JPEG_QUALITY), 90]) for me it solved the problem (python 2.7.2, opencv 2.4.1)
