flatten.py

Working with images a lot, thanks to my webcomic, becomes a lot easier when certain things are automated. For example, this script takes care of flattening an image (by removing alpha information), and even passes the output through pngcrush when applicable. It also includes a default output convention:

flatten.py

#!/usr/bin/python
from sys import argv, stderr, exit
from subprocess import Popen
from optparse import OptionParser, OptionValueError
from os import remove
from os import close as os_close
from re import compile as re_compile
from os.path import join, isfile
from tempfile import mkstemp


size = re_compile('^(.+)x(.+)$')

def check_size(option, opt_str, value, parser):
m = size.search(value)
if m:
parser.values.size = m.group(1), m.group(2)
else:
raise OptionValueError('Invalid size: %s' % value)

filext = re_compile('^(.+)\.(.+)$')
filext_png = re_compile('\.png$')

img_type = ['Bilevel', 'Grayscale', 'GrayscaleMatte', 'Palette', 'PaletteMatte', 'TrueColor', 'TrueColorMatte', 'ColorSeparate', 'ColorSeparationMatte', 'Optimize']
img_cspace = ['CMY', 'CMYK', 'Gray', 'HSB', 'HSL', 'HWB', 'Lab', 'Log', 'OHTA', 'Rec601Luma', 'Rec601YCbCr', 'Rec709Luma', 'Rec709YCbCr', 'RGB', 'sRGB', 'Transparent', 'XYZ', 'YCbCr', 'YCC', 'YIQ', 'YPbPr', 'YUV']

parser = OptionParser(usage = 'Usage: %prog [ options ] input [ output ]')
parser.add_option('-s', '--size', dest = 'size', type = 'string', action = 'callback', callback = check_size, default = None, help = 'The output size: WIDTHxHEIGHT')
parser.add_option('-n', '--no-clobber', dest = 'clobber', default = True, action = 'store_false', help = 'The output size: WIDTHxHEIGHT')
parser.add_option('-f', '--filter', dest = 'filter', default = 'Catrom', help = 'The filter to resize with if necessary.')
parser.add_option('-b', '--background', dest = 'background', default = 'white', help = 'The background when flattening.')
parser.add_option('-F', '--no-flatten', dest = 'flatten', default = True, action = 'store_false', help = 'Don\'t flatten the output.')
parser.add_option('-t', '--type', dest = 'type', type = 'string', default = None, help = 'The type of the output image: analogous to both -type and -colorspace in ImageMagick')
parser.add_option('-d', '--depth', dest = 'depth', type = 'int', default = None, help = 'The depth of the output image.')

options, args = parser.parse_args()
if len(args):
input = args.pop(0)
if isfile(input):
output = None
pngout = False
if len(args):
output = args.pop(0)
if filext_png.search(output):
pngout = True
else:
m = filext.search(input)
if not m is None:
output = '%s_small.%s' % (m.group(1), m.group(2))
if m.group(2) == 'png':
pngout = True
else:
output = '%s_small.png' % input
pngout = True
if not options.clobber and isfile(output):
print >>stderr, 'Output file exists:', output
exit(2)
# ACTUAL PROCESSING
args = ['convert', input]

if options.flatten:
args += ['-background', options.background, '-flatten', '+matte']
if not options.size is None:
args += ['-filter', options.filter, '-resize', '%sx%s' % options.size]

if not options.type is None:
if options.type in img_type:
args += ['-type', options.type]
if not options.depth is None:
args += ['-depth', str(options.depth)]
elif options.type in img_cspace:
args += ['-colorspace', options.type]
if not options.depth is None:
args += ['-depth', str(options.depth)]

if pngout:
fd, tmpfile = mkstemp()
os_close(fd)
args.append('png:' + tmpfile)
Popen(args).communicate()
Popen(('pngcrush', '-rem', 'sRGB', tmpfile, output)).communicate()
remove(tmpfile)
else:
args.append(output)
Popen(args).communicate()
# END
else:
print >>stderr, 'No such file:', input
exit(2)
else:
parser.print_help()
exit(1)% python flatten.py
Usage: flatten.py [ options ] input [ output ]

Options:
-h, --help show this help message and exit
-s SIZE, --size=SIZE The output size: WIDTHxHEIGHT
-n, --no-clobber The output size: WIDTHxHEIGHT
-f FILTER, --filter=FILTER
The filter to resize with if necessary.
-b BACKGROUND, --background=BACKGROUND
The background when flattening.
-F, --no-flatten Don't flatten the output.
-t TYPE, --type=TYPE The type of the output image: analogous to both -type
and -colorspace in ImageMagick
-d DEPTH, --depth=DEPTH
The depth of the output image.