Intenté leer el texto de la imagen usando Pytesseract. Recibo un mensaje de acceso denegado cuando ejecuto el siguiente script.

     from PIL import Image
     import pytesseract
     import cv2
     import os

     filename=r'C:\Users\ychandra\Documents\teaching-text-structure-3-728.jpg'
     pytesseract.pytesseract.tesseract_cmd = r'C:\Python27\Lib\site-packages\pytesseract'
     image=cv2.imread(filename)
     gray=cv2.cvtColor(image,cv2.COLOR_BGR2GRAY)

     gray=cv2.threshold(gray,0,255,cv2.THRESH_BINARY|cv2.THRESH_OTSU)[1]
     gray=cv2.medianBlur(gray,3)

     filename='{}.png'.format(os.getpid())
     cv2.imwrite(filename,gray)

     text=pytesseract.image_to_string(Image.open(filename))
     print text

     cv2.imshow("image",image)
     cv2.imshow("res",gray)
     cv2.waitKey(0)

cuando ejecuto el script me aparece debajo de Error

    Traceback (most recent call last):
    File "F:\opencv\New_folder_3\text_from_image.py", line 17, in <module>
text=pytesseract.image_to_string(Image.open(filename))
    File "C:\Python27\lib\site-packages\pytesseract\pytesseract.py", line 122, in image_to_string
config=config)
    File "C:\Python27\lib\site-packages\pytesseract\pytesseract.py", line 46, in run_tesseract
    proc = subprocess.Popen(command, stderr=subprocess.PIPE)
    File "C:\Python27\lib\subprocess.py", line 390, in __init__
errread, errwrite)
    File "C:\Python27\lib\subprocess.py", line 640, in _execute_child
startupinfo)
    WindowsError: [Error 5] Access is denied