Barcode
From Publication Station
Barcodes are essential encoding of characters onto black bars of different width and blanks.
There are there several types of barcodes, we'll look into:
Code 128
More info barcode code 128 encoding in:
#!/usr/bin/env python
import Image
import ImageDraw
# Info barcode code 128 encoding in http://grandzebu.net/informatique/codbar-en/code128.htm
# Copied from http://en.wikipedia.org/wiki/Code_128
# Value Weights 128A 128B 128C
CODE128_CHART = """
0 212222 space space 00
1 222122 ! ! 01
2 222221 " " 02
3 121223 # # 03
4 121322 $ $ 04
5 131222 % % 05
6 122213 & & 06
7 122312 ' ' 07
8 132212 ( ( 08
9 221213 ) ) 09
10 221312 * * 10
11 231212 + + 11
12 112232 , , 12
13 122132 - - 13
14 122231 . . 14
15 113222 / / 15
16 123122 0 0 16
17 123221 1 1 17
18 223211 2 2 18
19 221132 3 3 19
20 221231 4 4 20
21 213212 5 5 21
22 223112 6 6 22
23 312131 7 7 23
24 311222 8 8 24
25 321122 9 9 25
26 321221 : : 26
27 312212 ; ; 27
28 322112 < < 28
29 322211 = = 29
30 212123 > > 30
31 212321 ? ? 31
32 232121 @ @ 32
33 111323 A A 33
34 131123 B B 34
35 131321 C C 35
36 112313 D D 36
37 132113 E E 37
38 132311 F F 38
39 211313 G G 39
40 231113 H H 40
41 231311 I I 41
42 112133 J J 42
43 112331 K K 43
44 132131 L L 44
45 113123 M M 45
46 113321 N N 46
47 133121 O O 47
48 313121 P P 48
49 211331 Q Q 49
50 231131 R R 50
51 213113 S S 51
52 213311 T T 52
53 213131 U U 53
54 311123 V V 54
55 311321 W W 55
56 331121 X X 56
57 312113 Y Y 57
58 312311 Z Z 58
59 332111 [ [ 59
60 314111 \ \ 60
61 221411 ] ] 61
62 431111 ^ ^ 62
63 111224 _ _ 63
64 111422 NUL ` 64
65 121124 SOH a 65
66 121421 STX b 66
67 141122 ETX c 67
68 141221 EOT d 68
69 112214 ENQ e 69
70 112412 ACK f 70
71 122114 BEL g 71
72 122411 BS h 72
73 142112 HT i 73
74 142211 LF j 74
75 241211 VT k 75
76 221114 FF l 76
77 413111 CR m 77
78 241112 SO n 78
79 134111 SI o 79
80 111242 DLE p 80
81 121142 DC1 q 81
82 121241 DC2 r 82
83 114212 DC3 s 83
84 124112 DC4 t 84
85 124211 NAK u 85
86 411212 SYN v 86
87 421112 ETB w 87
88 421211 CAN x 88
89 212141 EM y 89
90 214121 SUB z 90
91 412121 ESC { 91
92 111143 FS | 92
93 111341 GS } 93
94 131141 RS ~ 94
95 114113 US DEL 95
96 114311 FNC3 FNC3 96
97 411113 FNC2 FNC2 97
98 411311 ShiftB ShiftA 98
99 113141 CodeC CodeC 99
100 114131 CodeB FNC4 CodeB
101 311141 FNC4 CodeA CodeA
102 411131 FNC1 FNC1 FNC1
103 211412 StartA StartA StartA
104 211214 StartB StartB StartB
105 211232 StartC StartC StartC
106 2331112 Stop Stop Stop
""".split()
VALUES = [int(value) for value in CODE128_CHART[0::5]]
WEIGHTS = dict(zip(VALUES, CODE128_CHART[1::5]))
CODE128A = dict(zip(CODE128_CHART[2::5], VALUES))
CODE128B = dict(zip(CODE128_CHART[3::5], VALUES))
CODE128C = dict(zip(CODE128_CHART[4::5], VALUES))
for charset in (CODE128A, CODE128B):
charset[' '] = charset.pop('space')
def code128_format(data):
"""
Generate an optimal barcode from ASCII text
"""
text = str(data)
pos = 0
length = len(text)
# Start Code
if text[:2].isdigit() and length > 1:
charset = CODE128C
codes = [charset['StartC']]
else:
charset = CODE128B
codes = [charset['StartB']]
# Data
while pos < length:
if charset is CODE128C:
if text[pos:pos+2].isdigit() and length - pos > 1:
# Encode Code C two characters at a time
codes.append(int(text[pos:pos+2]))
pos += 2
else:
# Switch to Code B
codes.append(charset['CodeB'])
charset = CODE128B
elif text[pos:pos+4].isdigit() and length - pos >= 4:
# Switch to Code C
codes.append(charset['CodeC'])
charset = CODE128C
else:
# Encode Code B one character at a time
codes.append(charset[text[pos]])
pos += 1
# Checksum
checksum = 0
for weight, code in enumerate(codes):
checksum += max(weight, 1) * code
codes.append(checksum % 103)
# Stop Code
codes.append(charset['Stop'])
return codes
def code128_image(data, height=100, thickness=3, quiet_zone=True):
if not data[-1] == CODE128B['Stop']:
data = code128_format(data)
barcode_widths = []
for code in data:
for weight in WEIGHTS[code]:
barcode_widths.append(int(weight) * thickness)
width = sum(barcode_widths)
x = 0
if quiet_zone:
width += 20 * thickness
x = 10 * thickness
# Monochrome Image
img = Image.new('1', (width, height), 1)
draw = ImageDraw.Draw(img)
draw_bar = True
for width in barcode_widths:
if draw_bar:
draw.rectangle(((x, 0), (x + width - 1, height)), fill=0)
draw_bar = not draw_bar
x += width
return img
