bookland/scan13

   1 #!/usr/bin/python
   2 #
   3 #   scan13 - utility to read bar codes from EPS files.
   4 #
   5 #   Should be able to handle all EAN-13 variants including ISBN with UPC5
   6 #   price code.
   7 #
   8 #   usage:
   9 #   scan13 <filename.eps>
  10 #
  11 #   Copyright (C) 2007 Judah Milgram
  12 #
  13 #   This program is free software; you can redistribute it and/or
  14 #   modify it under the terms of the GNU General Public License
  15 #   as published by the Free Software Foundation; either version 2
  16 #   of the License, or (at your option) any later version.
  17 #
  18 #   Because this program copies a portion of itself into its output
  19 #   file, its output files are also copyright the author and licensed
  20 #   under the GPL.  Relevant provisions of the GPL notwithstanding,
  21 #   the author licenses users to use and redistribute output files
  22 #   generated by this program without restriction.
  23 #
  24 #   This program is distributed in the hope that it will be useful,
  25 #   but WITHOUT ANY WARRANTY; without even the implied warranty of
  26 #   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  27 #   GNU General Public License for more details.
  28 #
  29 #   You should have received a copy of the GNU General Public License along
  30 #   with this program; if not, write to the Free Software Foundation, Inc.,
  31 #   59 Temple Place, Suite 330, Boston, MA 02111-1307, USA.
  32 #
  33
  34
  35 import getopt
  36 import os
  37 import Image
  38 import sys
  39 import productcode
  40 import re
  41 import tempfile
  42
  43
  44 YSIZE=2400
  45 STRIPCOMMAND = "pstopnm -pbm -stdout -portrait -ysize %d -xborder 0 -yborder 0 %%s 2> /dev/null | pnmcut -top %d -bottom %d" % (YSIZE,YSIZE/2,YSIZE/2)
  46
  47 EPSFILE = re.compile(".*\.eps",re.I)
  48
  49 def eps2pixels(f):
  50     if not EPSFILE.match(f):
  51         raise Exception
  52     tempfil = tempfile.mktemp()
  53     s = os.popen("%s > %s" % (STRIPCOMMAND%f,tempfil)).readline()
  54     z = Image.open(tempfil)
  55     w,h = z.size
  56     pix = z.load()
  57     pixels = []
  58     for i in range(w):
  59         pixels.append(pix[i,0])
  60     os.unlink(tempfil)
  61     return pixels
  62
  63 def pixels2bars(pixels):
  64     bars = []
  65     p = 1
  66     for i in range(1,len(pixels)):
  67         if pixels[i]!= pixels[i-1]:
  68             bars.append(p)
  69             p = 1
  70         else:
  71             p+=1
  72     bars.append(p)
  73     # bars are in pixels
  74     # reduce to module widths
  75     i,a = ean13index(bars)
  76     bars = bars[i:]
  77     for j in range(len(bars)):
  78         bars[j] = int(round(bars[j]/float(a)))
  79     ean13bars = bars
  80     i,a = upc5index(bars)
  81     upc5bars = bars[i:]
  82     return (ean13bars,upc5bars)
  83
  84 def upc5index(bars):
  85     # Looking for 3 bars in ean13 right guard
  86     # then long space
  87     # then first two bars in upc5 left guard
  88     for i in range(len(bars)):
  89         candidates = bars[i:i+5]
  90         a = min(candidates[:3] + candidates[4:])
  91         b = max(candidates[:3] + candidates[4:])
  92         c = candidates[3]
  93         err = 0.20
  94         nlong=8
  95         # sorry for the hard-coded magic number (8) ...
  96         if abs(1-float(a)/b) < err and c > nlong*a:
  97             return i+4,a
  98     return None
  99
 100
 101 def ean13index(bars):
 102     # index of EAN13 guard bars and module size
 103     for i in range(len(bars)):
 104         candidates = bars[i:i+3]
 105         a = min(candidates)
 106         b = max(candidates)
 107         err = 0.20
 108         if abs(1-float(a)/b) < err:
 109             return i,a
 110     return None
 111
 112 def bars2bits(bars):
 113     val = 1
 114     bits=[]
 115     for bar in bars:
 116         bits.extend(bar*[val])
 117         # flip val:
 118         val = val ^ 1
 119     return bits
 120
 121 def upc5digit(bits):
 122     bits = "".join(map(str,bits))
 123     for i in range(len(productcode.UPC5BITS)):
 124         dict = productcode.UPC5BITS[i]
 125         keys = dict.keys()
 126         for key in keys:
 127             if dict[key]==bits:
 128                 return i,key
 129     return None,None
 130
 131 def ean13digit(bits):
 132     bits = "".join(map(str,bits))
 133     for i in range(len(productcode.EAN13BITS)):
 134         dict = productcode.EAN13BITS[i]
 135         keys = dict.keys()
 136         for key in keys:
 137             if dict[key]==bits:
 138                 return i,key
 139
 140
 141 if __name__=="__main__":
 142
 143     MYNAME="scan13"
 144     MYVERSION="0.1"
 145     COPYRIGHT="(C) 2007 J. Milgram"
 146     VERSIONDATE = "Feb 2007"
 147     MAINTAINER = "bookland-bugs@cgpp.com"
 148     WARNING = "This is free software and comes with NO WARRANTY"
 149
 150     sys.stderr.write("%s\n" % WARNING)
 151
 152     filnam = sys.argv[1]
 153
 154     pixels = eps2pixels(filnam)
 155     ean13bars,upc5bars = pixels2bars(pixels)
 156     ean13bits = bars2bits(ean13bars)
 157     upc5bits = bars2bits(upc5bars)
 158
 159     NLEFT=3
 160     NCENTER=5
 161     ean13digits=[]
 162     ean13pattern=[]
 163     for i in range(6):
 164         i0 = i*7 + NLEFT
 165         i1 = i0+7
 166         digit,parity = ean13digit(ean13bits[i0:i1])
 167         ean13digits.append(digit)
 168         ean13pattern.append(parity)
 169     for i in range(6,12):
 170         i0 = i*7 + NLEFT + NCENTER
 171         i1 = (i+1)*7 + NLEFT + NCENTER
 172         digit,parity=ean13digit(ean13bits[i0:i1])
 173         ean13digits.append(digit)
 174         ean13pattern.append(parity)
 175     ean13pattern = "".join(ean13pattern)
 176     checkDigit = productcode.EAN13PARITY.index(ean13pattern)
 177     ean13digits.insert(0,checkDigit)
 178     ean13 = "".join(map(str,ean13digits))
 179
 180     NLEFT = 4
 181     upc5digits=[]
 182     upc5pattern=[]
 183     for i in range(5):
 184         # 9 = 7 bits + 2 "delineators"
 185         i0=i*9 + NLEFT
 186         i1=i0+9
 187         digit,parity = upc5digit(upc5bits[i0:i0+7])
 188         upc5digits.append(digit)
 189         upc5pattern.append(parity)
 190     upc5 = "".join(map(str,upc5digits))
 191
 192
 193     print ean13,upc5
 194