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Merge pull request #109 from JaapHaitsma/master

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Fix issue #72 grouping and make gridsize determination more robust.
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Daniel Beer 2021-06-21 11:48:10 +12:00 committed by GitHub
commit 0aa5e2ac27
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2 changed files with 29 additions and 150 deletions
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174
lib/identify.c
View file

@ -648,131 +648,31 @@ static void find_leftmost_to_line(void *user_data, int y, int left, int right)
} }
} }
/* Do a Bresenham scan from one point to another and count the number static double distance(struct quirc_point a, struct quirc_point b)
* of black/white transitions.
*/
static int timing_scan(const struct quirc *q,
const struct quirc_point *p0,
const struct quirc_point *p1)
{ {
int n = p1->x - p0->x; return sqrt((a.x - b.x)*(a.x - b.x) + (a.y - b.y)*(a.y - b.y));
int d = p1->y - p0->y;
int x = p0->x;
int y = p0->y;
int *dom, *nondom;
int dom_step;
int nondom_step;
int a = 0;
int i;
int run_length = 0;
int count = 0;
if (p0->x < 0 || p0->y < 0 || p0->x >= q->w || p0->y >= q->h)
return -1;
if (p1->x < 0 || p1->y < 0 || p1->x >= q->w || p1->y >= q->h)
return -1;
if (abs(n) > abs(d)) {
int swap = n;
n = d;
d = swap;
dom = &x;
nondom = &y;
} else {
dom = &y;
nondom = &x;
}
if (n < 0) {
n = -n;
nondom_step = -1;
} else {
nondom_step = 1;
}
if (d < 0) {
d = -d;
dom_step = -1;
} else {
dom_step = 1;
}
x = p0->x;
y = p0->y;
for (i = 0; i <= d; i++) {
int pixel;
if (y < 0 || y >= q->h || x < 0 || x >= q->w)
break;
pixel = q->pixels[y * q->w + x];
if (pixel) {
if (run_length >= 2)
count++;
run_length = 0;
} else {
run_length++;
}
a += n;
*dom += dom_step;
if (a >= d) {
*nondom += nondom_step;
a -= d;
}
}
return count;
} }
/* Estimate grid size by determing distance between capstones
/* Try the measure the timing pattern for a given QR code. This does
* not require the global perspective to have been set up, but it
* does require that the capstone corners have been set to their
* canonical rotation.
*
* For each capstone, we find a point in the middle of the ring band
* which is nearest the centre of the code. Using these points, we do
* a horizontal and a vertical timing scan.
*/ */
static int measure_timing_pattern(struct quirc *q, int index) static void measure_grid_size(struct quirc *q, int index)
{ {
struct quirc_grid *qr = &q->grids[index]; struct quirc_grid *qr = &q->grids[index];
int i;
int scan;
int ver;
int size;
for (i = 0; i < 3; i++) { struct quirc_capstone *a = &(q->capstones[qr->caps[0]]);
static const double us[] = {6.5, 6.5, 0.5}; struct quirc_capstone *b = &(q->capstones[qr->caps[1]]);
static const double vs[] = {0.5, 6.5, 6.5}; struct quirc_capstone *c = &(q->capstones[qr->caps[2]]);
struct quirc_capstone *cap = &q->capstones[qr->caps[i]];
perspective_map(cap->c, us[i], vs[i], &qr->tpep[i]); double ab = distance(b->corners[0], a->corners[3]);
} double capstone_ab_size = (distance(b->corners[0], b->corners[3]) + distance(a->corners[0], a->corners[3]))/2.0;
double ver_grid = 7.0 * ab / capstone_ab_size;
qr->hscan = timing_scan(q, &qr->tpep[1], &qr->tpep[2]); double bc = distance(b->corners[0], c->corners[1]);
qr->vscan = timing_scan(q, &qr->tpep[1], &qr->tpep[0]); double capstone_bc_size = (distance(b->corners[0], b->corners[1]) + distance(c->corners[0], c->corners[1]))/2.0;
double hor_grid = 7.0 * bc / capstone_bc_size;
scan = qr->hscan;
if (qr->vscan > scan) double grid_size_estimate = (ver_grid + hor_grid) / 2;
scan = qr->vscan;
qr->grid_size = 4*((int)(grid_size_estimate - 17.0 + 2.0) / 4) + 17;
/* If neither scan worked, we can't go any further. */
if (scan < 0)
return -1;
/* Choose the nearest allowable grid size */
size = scan * 2 + 13;
ver = (size - 15) / 4;
if (ver > QUIRC_MAX_VERSION) {
return -1;
}
qr->grid_size = ver * 4 + 17;
return 0;
} }
/* Read a cell from a grid using the currently set perspective /* Read a cell from a grid using the currently set perspective
@ -1036,12 +936,10 @@ static void record_qr_grid(struct quirc *q, int a, int b, int c)
cap->qr_grid = qr_index; cap->qr_grid = qr_index;
} }
/* Check the timing pattern. This doesn't require a perspective /* Check the timing pattern by measuring grid size. This doesn't require a perspective
* transform. * transform.
*/ */
if (measure_timing_pattern(q, qr_index) < 0) measure_grid_size(q, qr_index);
goto fail;
/* Make an estimate based for the alignment pattern based on extending /* Make an estimate based for the alignment pattern based on extending
* lines from capstones A and C. * lines from capstones A and C.
*/ */
@ -1108,31 +1006,16 @@ static void test_neighbours(struct quirc *q, int i,
const struct neighbour_list *hlist, const struct neighbour_list *hlist,
const struct neighbour_list *vlist) const struct neighbour_list *vlist)
{ {
int j, k;
double best_score = 0.0;
int best_h = -1, best_v = -1;
/* Test each possible grouping */ /* Test each possible grouping */
for (j = 0; j < hlist->count; j++) for (int j = 0; j < hlist->count; j++) {
for (k = 0; k < vlist->count; k++) { const struct neighbour *hn = &hlist->n[j];
const struct neighbour *hn = &hlist->n[j]; for (int k = 0; k < vlist->count; k++) {
const struct neighbour *vn = &vlist->n[k]; const struct neighbour *vn = &vlist->n[k];
double score = fabs(1.0 - hn->distance / vn->distance); double squareness = fabs(1.0 - hn->distance / vn->distance);
if (squareness < 0.2)
if (score > 2.5) record_qr_grid(q, hn->index, i, vn->index);
continue;
if (best_h < 0 || score < best_score) {
best_h = hn->index;
best_v = vn->index;
best_score = score;
}
} }
}
if (best_h < 0 || best_v < 0)
return;
record_qr_grid(q, best_h, i, best_v);
} }
static void test_grouping(struct quirc *q, unsigned int i) static void test_grouping(struct quirc *q, unsigned int i)
@ -1142,9 +1025,6 @@ static void test_grouping(struct quirc *q, unsigned int i)
struct neighbour_list hlist; struct neighbour_list hlist;
struct neighbour_list vlist; struct neighbour_list vlist;
if (c1->qr_grid >= 0)
return;
hlist.count = 0; hlist.count = 0;
vlist.count = 0; vlist.count = 0;
@ -1155,7 +1035,7 @@ static void test_grouping(struct quirc *q, unsigned int i)
struct quirc_capstone *c2 = &q->capstones[j]; struct quirc_capstone *c2 = &q->capstones[j];
double u, v; double u, v;
if (i == j || c2->qr_grid >= 0) if (i == j)
continue; continue;
perspective_unmap(c1->c, &c2->center, &u, &v); perspective_unmap(c1->c, &c2->center, &u, &v);

5
lib/quirc_internal.h
View file

@ -32,7 +32,8 @@
#define QUIRC_MAX_REGIONS 254 #define QUIRC_MAX_REGIONS 254
#endif #endif
#define QUIRC_MAX_CAPSTONES 32 #define QUIRC_MAX_CAPSTONES 32
#define QUIRC_MAX_GRIDS 8 #define QUIRC_MAX_GRIDS (QUIRC_MAX_CAPSTONES * 2)
#define QUIRC_PERSPECTIVE_PARAMS 8 #define QUIRC_PERSPECTIVE_PARAMS 8
#if QUIRC_MAX_REGIONS < UINT8_MAX #if QUIRC_MAX_REGIONS < UINT8_MAX
@ -72,8 +73,6 @@ struct quirc_grid {
/* Timing pattern endpoints */ /* Timing pattern endpoints */
struct quirc_point tpep[3]; struct quirc_point tpep[3];
int hscan;
int vscan;
/* Grid size and perspective transform */ /* Grid size and perspective transform */
int grid_size; int grid_size;