1 | /* |
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2 | * vbulletin.c: decode vbulletin captchas |
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3 | * $Id: vbulletin.c 482 2005-05-30 15:22:02Z sam $ |
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4 | * |
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5 | * Copyright: (c) 2005 Sam Hocevar <sam@zoy.org> |
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6 | * This program is free software; you can redistribute it and/or |
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7 | * modify it under the terms of the Do What The Fuck You Want To |
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8 | * Public License as published by Banlu Kemiyatorn. See |
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9 | * http://sam.zoy.org/projects/COPYING.WTFPL for more details. |
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10 | */ |
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11 | |
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12 | #include <stdio.h> |
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13 | #include <stdlib.h> |
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14 | #include <string.h> |
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15 | #include <limits.h> |
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16 | |
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17 | #include "config.h" |
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18 | #include "common.h" |
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19 | |
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20 | /* Main function */ |
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21 | char *decode_vbulletin(struct image *img) |
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22 | { |
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23 | static struct font *font = NULL; |
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24 | char *result; |
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25 | struct image *tmp; |
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26 | int limits[6] = { 26, 53, 80, 107, 134, 160 }; |
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27 | int x, y, r, g, b, i, j; |
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28 | |
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29 | if(!font) |
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30 | { |
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31 | font = font_load_fixed("font_vbulletin.png", |
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32 | "2346789ABCDEFGHJKLMNPRTWXYZ"); |
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33 | if(!font) |
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34 | exit(-1); |
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35 | } |
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36 | |
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37 | /* vBulletin captchas have 6 characters */ |
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38 | result = malloc(7 * sizeof(char)); |
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39 | strcpy(result, " "); |
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40 | |
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41 | /* half the captchas are inverse video; we set them back to normal */ |
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42 | tmp = image_dup(img); |
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43 | getpixel(tmp, 0, 0, &r, &g, &b); |
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44 | if(r < 50) |
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45 | filter_threshold(tmp, 128); |
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46 | else |
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47 | filter_threshold(tmp, -128); |
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48 | |
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49 | /* Remove garbage around the cells */ |
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50 | for(x = 0; x < tmp->width; x++) |
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51 | { |
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52 | for(y = 0; y < 15; y++) |
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53 | setpixel(tmp, x, y, 255, 255, 255); |
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54 | for(y = 45; y < tmp->height; y++) |
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55 | setpixel(tmp, x, y, 255, 255, 255); |
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56 | } |
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57 | |
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58 | for(x = 0; x < tmp->width; x++) |
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59 | { |
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60 | for(i = 0; i < 6; i++) |
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61 | if(x == limits[i]) |
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62 | break; |
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63 | if(i == 6) |
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64 | for(y = 15; y < 45; y++) |
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65 | setpixel(tmp, x, y, 255, 255, 255); |
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66 | else |
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67 | x += 11; |
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68 | } |
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69 | |
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70 | filter_black_stuff(tmp); |
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71 | filter_black_stuff(tmp); |
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72 | |
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73 | /* Fill letters in gray */ |
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74 | for(x = 26; x < 172; x++) |
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75 | { |
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76 | getpixel(tmp, x, 15, &r, &g, &b); |
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77 | if(r == 0) |
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78 | filter_flood_fill(tmp, x, 15, 127, 0, 255); |
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79 | } |
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80 | |
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81 | /* Find remaining black parts and remove them */ |
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82 | for(x = 26; x < 172; x++) |
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83 | for(y = 15; y < 45; y++) |
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84 | { |
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85 | getpixel(tmp, x, y, &r, &g, &b); |
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86 | if(r == 0) |
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87 | filter_flood_fill(tmp, x, y, 255, 255, 255); |
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88 | } |
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89 | |
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90 | /* Fill letters in black */ |
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91 | for(x = 26; x < 172; x++) |
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92 | { |
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93 | getpixel(tmp, x, 44, &r, &g, &b); |
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94 | if(r == 127) |
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95 | filter_flood_fill(tmp, x, 44, 0, 0, 0); |
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96 | } |
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97 | |
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98 | /* Find remaining gray parts and remove them */ |
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99 | for(x = 26; x < 172; x++) |
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100 | for(y = 15; y < 45; y++) |
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101 | { |
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102 | getpixel(tmp, x, y, &r, &g, &b); |
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103 | if(r == 127) |
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104 | filter_flood_fill(tmp, x, y, 255, 255, 255); |
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105 | } |
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106 | |
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107 | /* Guess all glyphs */ |
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108 | for(i = 0; i < 6; i++) |
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109 | { |
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110 | int mindist = INT_MAX, min = -1; |
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111 | for(j = 0; j < font->size; j++) |
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112 | { |
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113 | int dist = 0; |
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114 | for(y = 0; y < 30; y++) |
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115 | for(x = 0; x < 11; x++) |
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116 | { |
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117 | int r2, g2, b2; |
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118 | getpixel(font->img, 12 * j + x, y, &r, &g, &b); |
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119 | getpixel(tmp, limits[i] + x, 15 + y, &r2, &g2, &b2); |
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120 | dist += (r - r2) * (r - r2); |
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121 | } |
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122 | if(dist < mindist) |
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123 | { |
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124 | mindist = dist; |
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125 | min = j; |
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126 | } |
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127 | } |
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128 | result[i] = font->glyphs[min].c; |
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129 | } |
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130 | |
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131 | image_free(tmp); |
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132 | |
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133 | return result; |
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134 | } |
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135 | |
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