Permalink
Fetching contributors…
Cannot retrieve contributors at this time
executable file 538 lines (462 sloc) 15.7 KB
#!/usr/bin/env python
# $URL$
# $Rev$
# iccp
#
# International Color Consortium Profile
#
# Tools for manipulating ICC profiles.
#
# An ICC profile can be extracted from a PNG image (iCCP chunk).
#
#
# Non-standard ICCP tags.
#
# Apple use some (widespread but) non-standard tags. These can be
# displayed in Apple's ColorSync Utility.
# - 'vcgt' (Video Card Gamma Tag). Table to load into video
# card LUT to apply gamma.
# - 'ndin' Apple display native information.
# - 'dscm' Apple multi-localized description strings.
# - 'mmod' Apple display make and model information.
#
# References
#
# [ICC 2001] ICC Specification ICC.1:2001-04 (Profile version 2.4.0)
# [ICC 2004] ICC Specification ICC.1:2004-10 (Profile version 4.2.0.0)
import struct
import png
class FormatError(Exception):
pass
class Profile:
"""An International Color Consortium Profile (ICC Profile)."""
def __init__(self):
self.rawtagtable = None
self.rawtagdict = {}
self.d = dict()
def fromFile(self, inp, name='<unknown>'):
# See [ICC 2004]
profile = inp.read(128)
if len(profile) < 128:
raise FormatError("ICC Profile is too short.")
size, = struct.unpack('>L', profile[:4])
profile += inp.read(d['size'] - len(profile))
return self.fromString(profile, name)
def fromString(self, profile, name='<unknown>'):
self.d = dict()
d = self.d
if len(profile) < 128:
raise FormatError("ICC Profile is too short.")
d.update(
zip(['size', 'preferredCMM', 'version',
'profileclass', 'colourspace', 'pcs'],
struct.unpack('>L4sL4s4s4s', profile[:24])))
if len(profile) < d['size']:
warnings.warn(
'Profile size declared to be %d, but only got %d bytes' %
(d['size'], len(profile)))
d['version'] = '%08x' % d['version']
d['created'] = readICCdatetime(profile[24:36])
d.update(
zip(['acsp', 'platform', 'flag', 'manufacturer', 'model'],
struct.unpack('>4s4s3L', profile[36:56])))
if d['acsp'] != 'acsp':
warnings.warn('acsp field not present (not an ICC Profile?).')
d['deviceattributes'] = profile[56:64]
d['intent'], = struct.unpack('>L', profile[64:68])
d['pcsilluminant'] = readICCXYZNumber(profile[68:80])
d['creator'] = profile[80:84]
d['id'] = profile[84:100]
ntags, = struct.unpack('>L', profile[128:132])
d['ntags'] = ntags
fmt = '4s2L' * ntags
# tag table
tt = struct.unpack('>' + fmt, profile[132:132+12*ntags])
tt = group(tt, 3)
# Could (should) detect 2 or more tags having the same sig. But
# we don't. Two or more tags with the same sig is illegal per
# the ICC spec.
# Convert (sig,offset,size) triples into (sig,value) pairs.
rawtag = map(lambda x: (x[0], profile[x[1]:x[1]+x[2]]), tt)
self.rawtagtable = rawtag
self.rawtagdict = dict(rawtag)
tag = dict()
# Interpret the tags whose types we know about
for sig, v in rawtag:
if sig in tag:
warnings.warn("Duplicate tag %r found. Ignoring." % sig)
continue
v = ICCdecode(v)
if v is not None:
tag[sig] = v
self.tag = tag
return self
def greyInput(self):
"""Adjust ``self.d`` dictionary for greyscale input device.
``profileclass`` is 'scnr', ``colourspace`` is 'GRAY', ``pcs``
is 'XYZ '.
"""
self.d.update(dict(profileclass='scnr',
colourspace='GRAY', pcs='XYZ '))
return self
def maybeAddDefaults(self):
if self.rawtagdict:
return
self._addTags(
cprt='Copyright unknown.',
desc='created by $URL$ $Rev$',
wtpt=D50(),
)
def addTags(self, **k):
self.maybeAddDefaults()
self._addTags(**k)
def _addTags(self, **k):
"""Helper for :meth:`addTags`."""
for tag, thing in k.items():
if not isinstance(thing, (tuple, list)):
thing = (thing,)
typetag = defaulttagtype[tag]
self.rawtagdict[tag] = encode(typetag, *thing)
return self
def write(self, out):
"""Write ICC Profile to the file."""
if not self.rawtagtable:
self.rawtagtable = self.rawtagdict.items()
tags = tagblock(self.rawtagtable)
self.writeHeader(out, 128 + len(tags))
out.write(tags)
out.flush()
return self
def writeHeader(self, out, size=999):
"""Add default values to the instance's `d` dictionary, then
write a header out onto the file stream. The size of the
profile must be specified using the `size` argument.
"""
def defaultkey(d, key, value):
"""Add ``[key]==value`` to the dictionary `d`, but only if
it does not have that key already.
"""
if key in d:
return
d[key] = value
z = '\x00' * 4
defaults = dict(preferredCMM=z,
version='02000000',
profileclass=z,
colourspace=z,
pcs='XYZ ',
created=writeICCdatetime(),
acsp='acsp',
platform=z,
flag=0,
manufacturer=z,
model=0,
deviceattributes=0,
intent=0,
pcsilluminant=encodefuns()['XYZ'](*D50()),
creator=z,
)
for k,v in defaults.items():
defaultkey(self.d, k, v)
hl = map(self.d.__getitem__,
['preferredCMM', 'version', 'profileclass', 'colourspace',
'pcs', 'created', 'acsp', 'platform', 'flag',
'manufacturer', 'model', 'deviceattributes', 'intent',
'pcsilluminant', 'creator'])
# Convert to struct.pack input
hl[1] = int(hl[1], 16)
out.write(struct.pack('>L4sL4s4s4s12s4s4sL4sLQL12s4s', size, *hl))
out.write('\x00' * 44)
return self
def encodefuns():
"""Returns a dictionary mapping ICC type signature sig to encoding
function. Each function returns a string comprising the content of
the encoded value. To form the full value, the type sig and the 4
zero bytes should be prefixed (8 bytes).
"""
def desc(ascii):
"""Return textDescription type [ICC 2001] 6.5.17. The ASCII part is
filled in with the string `ascii`, the Unicode and ScriptCode parts
are empty."""
ascii += '\x00'
l = len(ascii)
return struct.pack('>L%ds2LHB67s' % l,
l, ascii, 0, 0, 0, 0, '')
def text(ascii):
"""Return textType [ICC 2001] 6.5.18."""
return ascii + '\x00'
def curv(f=None, n=256):
"""Return a curveType, [ICC 2001] 6.5.3. If no arguments are
supplied then a TRC for a linear response is generated (no entries).
If an argument is supplied and it is a number (for *f* to be a
number it means that ``float(f)==f``) then a TRC for that
gamma value is generated.
Otherwise `f` is assumed to be a function that maps [0.0, 1.0] to
[0.0, 1.0]; an `n` element table is generated for it.
"""
if f is None:
return struct.pack('>L', 0)
try:
if float(f) == f:
return struct.pack('>LH', 1, int(round(f*2**8)))
except (TypeError, ValueError):
pass
assert n >= 2
table = []
M = float(n-1)
for i in range(n):
x = i/M
table.append(int(round(f(x) * 65535)))
return struct.pack('>L%dH' % n, n, *table)
def XYZ(*l):
return struct.pack('>3l', *map(fs15f16, l))
return locals()
# Tag type defaults.
# Most tags can only have one or a few tag types.
# When encoding, we associate a default tag type with each tag so that
# the encoding is implicit.
defaulttagtype=dict(
A2B0='mft1',
A2B1='mft1',
A2B2='mft1',
bXYZ='XYZ',
bTRC='curv',
B2A0='mft1',
B2A1='mft1',
B2A2='mft1',
calt='dtim',
targ='text',
chad='sf32',
chrm='chrm',
cprt='desc',
crdi='crdi',
dmnd='desc',
dmdd='desc',
devs='',
gamt='mft1',
kTRC='curv',
gXYZ='XYZ',
gTRC='curv',
lumi='XYZ',
meas='',
bkpt='XYZ',
wtpt='XYZ',
ncol='',
ncl2='',
resp='',
pre0='mft1',
pre1='mft1',
pre2='mft1',
desc='desc',
pseq='',
psd0='data',
psd1='data',
psd2='data',
psd3='data',
ps2s='data',
ps2i='data',
rXYZ='XYZ',
rTRC='curv',
scrd='desc',
scrn='',
tech='sig',
bfd='',
vued='desc',
view='view',
)
def encode(tsig, *l):
"""Encode a Python value as an ICC type. `tsig` is the type
signature to (the first 4 bytes of the encoded value, see [ICC 2004]
section 10.
"""
fun = encodefuns()
if tsig not in fun:
raise "No encoder for type %r." % tsig
v = fun[tsig](*l)
# Padd tsig out with spaces.
tsig = (tsig + ' ')[:4]
return tsig + '\x00'*4 + v
def tagblock(tag):
"""`tag` should be a list of (*signature*, *element*) pairs, where
*signature* (the key) is a length 4 string, and *element* is the
content of the tag element (another string).
The entire tag block (consisting of first a table and then the
element data) is constructed and returned as a string.
"""
n = len(tag)
tablelen = 12*n
# Build the tag table in two parts. A list of 12-byte tags, and a
# string of element data. Offset is the offset from the start of
# the profile to the start of the element data (so the offset for
# the next element is this offset plus the length of the element
# string so far).
offset = 128 + tablelen + 4
# The table. As a string.
table = ''
# The element data
element = ''
for k,v in tag:
table += struct.pack('>4s2L', k, offset + len(element), len(v))
element += v
return struct.pack('>L', n) + table + element
def iccp(out, inp):
profile = Profile().fromString(*profileFromPNG(inp))
print >>out, profile.d
print >>out, map(lambda x: x[0], profile.rawtagtable)
print >>out, profile.tag
def profileFromPNG(inp):
"""Extract profile from PNG file. Return (*profile*, *name*)
pair."""
r = png.Reader(file=inp)
_,chunk = r.chunk('iCCP')
i = chunk.index('\x00')
name = chunk[:i]
compression = chunk[i+1]
assert compression == chr(0)
profile = chunk[i+2:].decode('zlib')
return profile, name
def iccpout(out, inp):
"""Extract ICC Profile from PNG file `inp` and write it to
the file `out`."""
out.write(profileFromPNG(inp)[0])
def fs15f16(x):
"""Convert float to ICC s15Fixed16Number (as a Python ``int``)."""
return int(round(x * 2**16))
def D50():
"""Return D50 illuminant as an (X,Y,Z) triple."""
# See [ICC 2001] A.1
return (0.9642, 1.0000, 0.8249)
def writeICCdatetime(t=None):
"""`t` should be a gmtime tuple (as returned from
``time.gmtime()``). If not supplied, the current time will be used.
Return an ICC dateTimeNumber in a 12 byte string.
"""
import time
if t is None:
t = time.gmtime()
return struct.pack('>6H', *t[:6])
def readICCdatetime(s):
"""Convert from 12 byte ICC representation of dateTimeNumber to
ISO8601 string. See [ICC 2004] 5.1.1"""
return '%04d-%02d-%02dT%02d:%02d:%02dZ' % struct.unpack('>6H', s)
def readICCXYZNumber(s):
"""Convert from 12 byte ICC representation of XYZNumber to (x,y,z)
triple of floats. See [ICC 2004] 5.1.11"""
return s15f16l(s)
def s15f16l(s):
"""Convert sequence of ICC s15Fixed16 to list of float."""
# Note: As long as float has at least 32 bits of mantissa, all
# values are preserved.
n = len(s)//4
t = struct.unpack('>%dl' % n, s)
return map((2**-16).__mul__, t)
# Several types and their byte encodings are defined by [ICC 2004]
# section 10. When encoded, a value begins with a 4 byte type
# signature. We use the same 4 byte type signature in the names of the
# Python functions that decode the type into a Pythonic representation.
def ICCdecode(s):
"""Take an ICC encoded tag, and dispatch on its type signature
(first 4 bytes) to decode it into a Python value. Pair (*sig*,
*value*) is returned, where *sig* is a 4 byte string, and *value* is
some Python value determined by the content and type.
"""
sig = s[0:4].strip()
f=dict(text=RDtext,
XYZ=RDXYZ,
curv=RDcurv,
vcgt=RDvcgt,
sf32=RDsf32,
)
if sig not in f:
return None
return (sig, f[sig](s))
def RDXYZ(s):
"""Convert ICC XYZType to rank 1 array of trimulus values."""
# See [ICC 2001] 6.5.26
assert s[0:4] == 'XYZ '
return readICCXYZNumber(s[8:])
def RDsf32(s):
"""Convert ICC s15Fixed16ArrayType to list of float."""
# See [ICC 2004] 10.18
assert s[0:4] == 'sf32'
return s15f16l(s[8:])
def RDmluc(s):
"""Convert ICC multiLocalizedUnicodeType. This types encodes
several strings together with a language/country code for each
string. A list of (*lc*, *string*) pairs is returned where *lc* is
the 4 byte language/country code, and *string* is the string
corresponding to that code. It seems unlikely that the same
language/country code will appear more than once with different
strings, but the ICC standard does not prohibit it."""
# See [ICC 2004] 10.13
assert s[0:4] == 'mluc'
n,sz = struct.unpack('>2L', s[8:16])
assert sz == 12
record = []
for i in range(n):
lc,l,o = struct.unpack('4s2L', s[16+12*n:28+12*n])
record.append(lc, s[o:o+l])
# How are strings encoded?
return record
def RDtext(s):
"""Convert ICC textType to Python string."""
# Note: type not specified or used in [ICC 2004], only in older
# [ICC 2001].
# See [ICC 2001] 6.5.18
assert s[0:4] == 'text'
return s[8:-1]
def RDcurv(s):
"""Convert ICC curveType."""
# See [ICC 2001] 6.5.3
assert s[0:4] == 'curv'
count, = struct.unpack('>L', s[8:12])
if count == 0:
return dict(gamma=1)
table = struct.unpack('>%dH' % count, s[12:])
if count == 1:
return dict(gamma=table[0]*2**-8)
return table
def RDvcgt(s):
"""Convert Apple CMVideoCardGammaType."""
# See
# http://developer.apple.com/documentation/GraphicsImaging/Reference/ColorSync_Manager/Reference/reference.html#//apple_ref/c/tdef/CMVideoCardGammaType
assert s[0:4] == 'vcgt'
tagtype, = struct.unpack('>L', s[8:12])
if tagtype != 0:
return s[8:]
if tagtype == 0:
# Table.
channels,count,size = struct.unpack('>3H', s[12:18])
if size == 1:
fmt = 'B'
elif size == 2:
fmt = 'H'
else:
return s[8:]
l = len(s[18:])//size
t = struct.unpack('>%d%s' % (l, fmt), s[18:])
t = group(t, count)
return size, t
return s[8:]
def group(s, n):
# See
# http://www.python.org/doc/2.6/library/functions.html#zip
return zip(*[iter(s)]*n)
def main(argv=None):
import sys
from getopt import getopt
if argv is None:
argv = sys.argv
argv = argv[1:]
opt,arg = getopt(argv, 'o:')
if len(arg) > 0:
inp = open(arg[0], 'rb')
else:
inp = sys.stdin
for o,v in opt:
if o == '-o':
f = open(v, 'wb')
return iccpout(f, inp)
return iccp(sys.stdout, inp)
if __name__ == '__main__':
main()