/* Main function */
char *decode_authimage(struct image *img)
{
static struct font *font = NULL;
char *result;
struct image *tmp;
int x, y, r, g, b, i;
if(!font)
{
font = font_load_fixed(DECODER, "font.png",
"0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ");
if(!font)
exit(-1);
}
/* authimage captchas have 6 characters */
result = malloc(7 * sizeof(char));
memset(result, '\0', 7);
/* double the captcha size for better accuracy in the rotation */
tmp = image_dup(img);
filter_scale(tmp, 2.0);
getpixel(tmp, 0, 0, &r, &g, &b);
filter_threshold(tmp, r * 3 / 4);
filter_smooth(tmp);
filter_threshold(tmp, 220);
for(i = 0; i < 6; i++)
{
int mindiff = INT_MAX, minch = -1, ch;
for(ch = 0; ch < font->size; ch++)
{
int diff = 0;
for(y = 0; y < 7; y++)
{
for(x = 0; x < 5; x++)
{
int newx, newy, r2;
newx = 35.0 + (x + 6 * i) * 218.0 / 34.0 + y * 5.0 / 6.0 + 0.5;
newy = 33.0 - (x + 6 * i) * 18.0 / 34.0 + y * 42.0 / 6.0 + 0.5;
getpixel(tmp, newx, newy, &r, &g, &b);
getpixel(font->img, x + 6 * ch, y, &r2, &g, &b);
diff += (r - r2) * (r - r2);
}
}
if(diff < mindiff)
{
mindiff = diff;
minch = ch;
}
}
result[i] = font->glyphs[minch].c;
}
image_free(tmp);
return result;
}
/* Main function */
char *decode_lmt(struct image *img)
{
struct image *tmp;
/* lmt captchas have 3 characters */
result = malloc(4 * sizeof(char));
strcpy(result, " ");
tmp = image_dup(img);
filter_contrast(tmp);
filter_black_stuff(tmp);
filter_smooth(tmp);
filter_median(tmp);
find_glyphs(tmp);
image_free(tmp);
return result;
}
static void find_glyphs(struct image *img)
{
#define DELTA 2
static struct font *font;
int x, y, i = 0;
int r, g, b;
int xmin, xmax, ymin, ymax, startx = 0, cur = 0;
int bestdist, bestx, besty, bestch;
if(!font)
{
font = font_load_variable(DECODER, "freesans_24_09AZ.bmp",
"0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ");
filter_smooth(font->img);
if(!font)
exit(1);
}
while(cur < 3)
{
/* Try to find 1st letter */
bestdist = INT_MAX;
for(i = 0; i < font->size; i++)
{
int localmin = INT_MAX, localx, localy;
xmin = font->glyphs[i].xmin - DELTA;
ymin = font->glyphs[i].ymin;
xmax = font->glyphs[i].xmax + DELTA;
ymax = font->glyphs[i].ymax;
for(y = -5; y < 5; y++)
{
for(x = startx; x < startx + 15; x++)
{
int z, t, dist;
dist = 0;
for(t = 0; t < ymax - ymin; t++)
for(z = 0; z < xmax - xmin; z++)
{
int r2;
getgray(font->img, xmin + z, ymin + t, &r);
getgray(img, x + z, y + t, &r2);
dist += (r - r2) * (r - r2);
}
dist = dist / (xmax - xmin - 2 * DELTA);
if(dist < localmin)
{
localmin = dist;
localx = x;
localy = y;
}
}
}
if(localmin < bestdist)
{
bestdist = localmin;
bestx = localx;
besty = localy;
bestch = i;
}
}
/* Print min glyph */
#if 0
xmin = font->glyphs[bestch].xmin - DELTA;
ymin = font->glyphs[bestch].ymin;
xmax = font->glyphs[bestch].xmax + DELTA;
ymax = font->glyphs[bestch].ymax;
for(y = 0; y < ymax - ymin; y++)
for(x = 0; x < xmax - xmin; x++)
{
getpixel(font->img, xmin + x, ymin + y, &r, &g, &b);
if(r > 128)
{
getpixel(img, bestx + x, besty + y, &r, &g, &b);
r = 255;
}
setpixel(img, bestx + x, besty + y, r, g, b);
}
#endif
startx = bestx + font->glyphs[bestch].xmax - font->glyphs[bestch].xmin;
result[cur++] = font->glyphs[bestch].c;
}
}