pipeline_v3.py

for source in SOURCES:
    print('Processing:', source)
    img = io.imread(source)
    img = cv2.cvtColor(img, cv2.COLOR_RGB2GRAY)
    filename = os.path.basename(source)
    cv2.imwrite('processed_' + filename, img)

# Output
# Processing: lena.jpg
# Processing: monarch.png
# Processing: https://github.com/opencv/opencv/raw/master/samples/data/aero3.jpg
# Processing: https://github.com/opencv/opencv/raw/master/samples/data/fruits.jpg