Python ERROR : ValueError: I/O operation on closed file.

For a quick fix, save the standard stdout in a different variable, then redirect to it after that close.

# Simple image to string
saved_stdout = sys.stdout
sys.stdout = open('file.txt', 'w')
print (pytesseract.image_to_string(Image.open('Ke.png')))
sys.stdout.close()

sys.stdout = saved_stdout