error: OpenCV(3.4.1) C:\Miniconda3\conda-bld\opencv-suite_1533128839831\work\modules\highgui\src\window.cpp:356: error: (-215) size.width>0 && size.height>0 in function cv::imshow

edit

You need to add filename.

img=cv2.imread("C:/Users/ravik_000/Desktop/photo/filename+extension",1)

your image was never read (imread() returns None silently on failure, and you will get errors in the next lines, trying to process an invalid image).

please make it a habit to check EVERY imread() call like:

im = cv2.imread(somepath)
if not im:
       # fail, you can't go on ! check the path, and try again