convert images linux / python

# python linux create sepia / high contrast / black&white images
# from current images in directory

import os
ds = ['hi-con','sepia','bw']
for d in ds:
    try:
        os.mkdir(d)
    except:
        pass
for img in os.listdir("."):
    if ".jpg" in img.lower():
        print('Converting',img)
        hc_img = img
        sep_img = img
        gray_img = img

        os.system("convert -level 07%,87% "+hc_img+" ./hi-con/hi-cont-"+img)
        os.system("convert -sepia-tone 92% "+sep_img+" ./sepia/sepia-"+img)
        os.system("convert -colorspace Gray "+gray_img+" ./bw/Gray-Scale-"+img)
    else:
        print(img)
        print('?????')