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I am trying to read images directly as black and white.

I recently updated my OpenCv version to 3.0.0-dev, and the code that I used before does not work anymore.

   img = cv2.imread(f, cv2.CV_LOAD_IMAGE_GRAYSCALE)

works fine for 2.4 but does not work for the new version, as there is no field CV_LOAD_IMAGE_GRAYSCALE.

Any suggestions?

Note: I know that cv2.imread(f,0) will work, but I do not like having unnamed constants in my code. Thanks!

elaRosca
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3 Answers3

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The flag has been renamed to cv2.IMREAD_GRAYSCALE. Generally speaking, flags now have names prefixed in a manner that relates to the function to which they refer. (e.g. imread flags start with IMREAD_, cvtColor flags start with COLOR_, etc.)

Aurelius
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    Awesome. Thanks for the explanation, will probably help in the future as well. – elaRosca Apr 28 '14 at 15:39
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    The documentation should be updated accordingly: http://docs.opencv.org/trunk/modules/imgcodecs/doc/reading_and_writing_images.html?highlight=imread#Mat imread(const String& filename, int flags) – Eduard Feicho Feb 04 '15 at 18:56
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Try this it works for me

import cv2
im_gray = cv2.imread('gray_image.png', cv2.IMREAD_GRAYSCALE)
thresh = 127
im_bw = cv2.threshold(im_gray, thresh, 255, cv2.THRESH_BINARY)[1]
cv2.imwrite('blackwhite.png', im_bw)
Jibin Mathew
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1

Try this, it works for me everytime

import cv2
gray_img = cv2.imread('img.png', 0)
cv2.imshow(gray_img)
Sarthak Vajpayee
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    My guess is downvote(s) because OP wrote "I know that cv2.imread(f,0) will work, but I do not like having unnamed constants in my code." – eric Jul 06 '19 at 14:07