This takes a raw Apple IIgs $C1 image and writes zeros to every other "scanline".

c1-striper.py

# Invoke like:
# $ python stripe.py example.c1 output_dir

from sys import argv
from array import array
import os

data = array('B')

with open(argv[1], 'rb') as input_img:
    data = input_img.read()
outdata = bytearray(data)
# do every other line from 0-199.  you can change 0 to 1 if you want odd lines
for line in range(0,200,2):
  # calculate beginning of line (each line is 160 ($A0) bytes)
  offset = 0xA0 * line
  for b in range(0,0xA0):
    # write 00's
    outdata[offset+b] = 0x00

# save file to output_dir
out_file = argv[2] + os.path.basename(argv[1])
newFile = open(out_file, "wb")
newFile.write(outdata)
print("Wrote {} bytes to {}.".format(len(outdata),out_file))