cv2_imread can not load JPEG

[Zhicheng Cui]

When I use cv2.imread() function to read a jpeg file, it always return None value.

However, it can read .png file correctly.

So what should I do to let cv2.imread support jpg format.

Thanks.

[Michael Beyeler]

Hi Zhicheng,

You are correct:

>>> myJpg = cv2.imread('myfile.jpg')

is the right way to read a JPG file in OpenCV 2:

http://docs.opencv.org/2.4/modules/highgui/doc/reading_and_writing_images_and_video.html#imread

However, the link above says that on some Unix platforms, you need to have the correct libraries installed (such as libjpeg-dev). Is it possible that you're on Linux?

Check this guide for help (Step 4):

http://www.askaswiss.com/2016/01/how-to-install-opencv-3-1-python-ubuntu-14-04.html

The line you want is:

$ sudo apt-get install libjpeg-dev libjpeg libjpeg-dbg libjpeg-progs

Best,

Michael