使用 cv2 和 python 打印图像

Question

When I use cv2.imshow , it works and the picture shows. but when I want to save it in a folder through using cv2.imwrite:

test_image = cv2.imread("/Users/Capstone-Project-1/test/000002806137.jpg")
test_image = cv2.resize(test_image, (512,256))/255.0
test_image = np.rollaxis(test_image, axis=2, start=0)
_, _, ti = test(lane_agent, np.array([test_image])) 

cv2.imshow("test", ti[0])
cv2.waitKey(0) 
cv2.imwrite('/Users/Capstone-Project-1/Deep Neural 
Networks/save_test/image_result.png',test_image)

it gives me the error below:

error: (-215:Assertion failed) image.channels() == 1 || image.channels() == 3 || 
image.channels() == 4 in function 'imwrite_'

Any suggestions how to fix the issue?

Answer 1

Maybe you have to do it like these:

path = 'D:/OpenCV/Scripts/Images'
cv2.imwrite(os.path.join(path , 'filename.png'), img)

Answer 2

why you use test_image and not ti[0] , the same frame you want to show?

have you tried this?

cv2.imwrite('/Users/Capstone-Project-1/Deep Neural Networks/save_test/image_result.png', ti[0])

do you have the same error?

Answer 3

test_image.shape[-1] needs to be 1 (monchrome), 3 (RGB) or 4 (RGBA)

Since you start as jpg , the data is probably RGB, so your shape after cv2.resize is (512, 256, 3)

When you do:

 test_image = np.rollaxis(test_image, axis=2, start=0)

your axes change and your shape becomes (3, 512, 256) . Now it isn't recognized as an image anymore, and imwrite fails.