A small script to send colored- and bw-pages to seperate printers.

colorsaver.py

#!/usr/bin/env python
# coding: utf-8

import argparse
import itertools
import re
import subprocess

def run_coverage(filename, gs):
    """
    Run ghostscript to determine the color-coverage of each page.
    """
    output = subprocess.check_output('{} -o - -sDEVICE=inkcov {}'.format(gs, filename).split())
    # Scan through the output, match the pagenumber and color-components.
    output = re.findall('^Page ([0-9]+)\n (0\.\d+)  (0\.\d+)  (0\.\d+)  (0\.\d+).+$',
                        output, re.MULTILINE)
    pages = []
    for page in output:
        # Page number
        p = int(page[0])
        c, m, y, k = (float(col) for col in page[1:])
        # Colored pages have non-zero color components.
        colored = c > 0 or m > 0 or y > 0
        # Appends page-number and boolean flag.
        pages.append((p, colored))
    return pages

def lp_commands(filename, pages, bwprinter, colprinter, lp):
    """
    Determine appropriate lp commands to print the page. This will sort the
    pages and group adjacent colored/uncolored pages together.
    """
    # Sort by pagenumber.
    pages = sorted(pages, key=lambda x: x[0])
    commands = []
    for colored, pages in itertools.groupby(pages, lambda x: x[1]):
        # The join later requires strings. Also pages is now an iterator, not a list.
        pages = list(str(page[0]) for page in pages)
        commands.append('{lp} -d {printer} -P {pages} {filename}'.format(
            lp=lp,
            printer=colprinter if colored else bwprinter,
            pages=','.join(pages),
            filename=filename
        ))
    return commands

def parse_arguments():
    """
    Parse arguments.
    """
    parser = argparse.ArgumentParser(description='Generate lp printing script, ' +
                                     'separating colorless and colored pages.')
    parser.add_argument('-d', help='Destination printer for grayscale pages.',
                        type=str, required=True, metavar='DESTBW')
    parser.add_argument('--col', help='Destination printer for colored pages.' +
                        '\nDefault is B/W printer with "_color" suffix.',
                        type=str, metavar='DESTCOL')
    parser.add_argument('--ghostscript', help='Path to the ghostscript binary',
                        type=str, default='gs', metavar='GS')
    parser.add_argument('--lp', help='Path to the lp binary',
                        type=str, default='lp')
    parser.add_argument('--dry-run', help='Don\'t run lp, just print the commands',
                        action='store_true', dest='dryrun')
    parser.add_argument('inputfile', help='The PDF input file',
                        type=str, nargs=1)
    parser.set_defaults(dryrun=False)
    return parser.parse_args()

def main():
    args = parse_arguments()
    filename = args.inputfile[0]
    bwprinter = args.d
    if args.col is not None:
        colprinter = args.col
    else:
        colprinter = bwprinter + '_color'
    pages = run_coverage(filename, args.ghostscript)
    commands = lp_commands(filename, pages, bwprinter, colprinter, args.lp)
    if args.dryrun:
        for cmd in commands:
            print(cmd)
    else:
        subprocess.check_call(cmd.split())

if __name__ == '__main__':
    main()