summaryrefslogtreecommitdiff
diff options
context:
space:
mode:
authorBenjamin Franzke <benjaminfranzke@googlemail.com>2012-04-26 05:46:04 +0200
committerBenjamin Franzke <benjaminfranzke@googlemail.com>2012-04-26 07:05:22 +0200
commit59e2caae78dfab3fa2afb8aa63572b70cf6b94e7 (patch)
tree725574f166c802816e271cb9c1640ba73a4672d7
parentdd2d59a1b26437904744d0604e85dfdcb6fbad27 (diff)
downloadcv-59e2caae78dfab3fa2afb8aa63572b70cf6b94e7.zip
cv-59e2caae78dfab3fa2afb8aa63572b70cf6b94e7.tar.gz
cv-59e2caae78dfab3fa2afb8aa63572b70cf6b94e7.tar.bz2
Add harris detector
-rw-r--r--Makefile6
-rw-r--r--harris.c230
2 files changed, 235 insertions, 1 deletions
diff --git a/Makefile b/Makefile
index 0e7e3a5..45ce1bf 100644
--- a/Makefile
+++ b/Makefile
@@ -25,7 +25,10 @@ cvg_LIBS=$(shell pkg-config --libs gtk+-3.0 glib-2.0 gmodule-2.0 opencv)
hst_CFLAGS=$(shell pkg-config --cflags gdk-pixbuf-2.0 glib-2.0)
hst_LIBS=$(shell pkg-config --libs gdk-pixbuf-2.0 glib-2.0)
-PROGS = wimmel wimmel_gl roi capture unvignette cvg hst
+harris_CFLAGS=$(shell pkg-config --cflags gdk-pixbuf-2.0 glib-2.0)
+harris_LIBS=$(shell pkg-config --libs gdk-pixbuf-2.0 glib-2.0)
+
+PROGS = wimmel wimmel_gl roi capture unvignette cvg hst harris
OBJS = $(PROGS:=.o) util.o
all: $(PROGS)
@@ -37,6 +40,7 @@ capture: capture.o
unvignette: unvignette.o
cvg: cvg.o
hst: hst.o
+harris: harris.o
.PHONY: clean all
diff --git a/harris.c b/harris.c
new file mode 100644
index 0000000..fab5141
--- /dev/null
+++ b/harris.c
@@ -0,0 +1,230 @@
+#include <stdlib.h>
+#include <string.h>
+#include <math.h>
+#include <gdk-pixbuf/gdk-pixbuf.h>
+
+struct mat2 {
+ float a1, a2, b1, b2;
+ float mc;
+};
+
+static inline float
+det(struct mat2 *m)
+{
+ return m->a1 * m->b2 - m->a2 * m->b1;
+}
+
+static inline float
+trace(struct mat2 *m)
+{
+ return m->a1 + m->b2;
+}
+
+static inline void
+pixbuf_get(GdkPixbuf *pixbuf, guchar **pixels,
+ gint *width, gint *height, gint *nch, gint *stride)
+{
+ if (pixels) *pixels = gdk_pixbuf_get_pixels(pixbuf);
+ if (width) *width = gdk_pixbuf_get_width(pixbuf);
+ if (height) *height = gdk_pixbuf_get_height(pixbuf);
+ if (nch) *nch = gdk_pixbuf_get_n_channels(pixbuf);
+ if (stride) *stride = gdk_pixbuf_get_rowstride(pixbuf);
+}
+
+static void
+grey_scale(GdkPixbuf *image)
+{
+ gint Y, x, y, width, height, nch, stride;
+ guchar *p, *row;
+
+ pixbuf_get(image, &row, &width, &height, &nch, &stride);
+ for (y = 0; y < height; ++y, row += stride) {
+ for (x = 0, p = row; x < width; ++x, p += nch) {
+ Y = 0.299 * p[0] + 0.587 * p[1] + 0.115 * p[2];
+ p[0] = p[1] = p[2] = Y;
+ }
+ }
+}
+
+int *
+conv(GdkPixbuf *pixbuf, gint *operator, gint block_size)
+{
+ gint Y, i, j, x, y, width, height, nch, stride;
+ guchar *p, *row, *v;
+ int *out;
+
+ pixbuf_get(pixbuf, &row, &width, &height, &nch, &stride);
+
+ out = malloc(width * height * sizeof *out);
+ if (!out)
+ return NULL;
+ for (y = 0; y < height; ++y, row += stride) {
+ for (x = 0, p = row; x < width; ++x, p += nch) {
+ Y = 0;
+ for (i = 0; i < block_size; ++i) {
+ for (j = 0; j < block_size; ++j) {
+ /* TODO: fix clamping */
+ v = p + (CLAMP((j-block_size/2), 0, width-1) * stride +
+ CLAMP((i-block_size/2), 0, height-1) * nch);
+ Y += v[0] * operator[j*block_size + i];
+ }
+ }
+ out[y * width + x] = Y/4;
+ }
+ }
+
+ return out;
+}
+
+struct mat2 *
+multiply(int *deriv_x, int *deriv_y, int width, int height)
+{
+ struct mat2 *m, *pm;
+ int *px, *py;
+ int i, n;
+
+ n = width * height;
+ m = calloc(n, sizeof *m);
+ if (!m)
+ return NULL;
+ px = deriv_x;
+ py = deriv_y;
+ pm = m;
+ for (i = 0; i < n; ++i) {
+ pm->a1 = *px * *px;
+ pm->a2 = pm->b1 = *px * *py;
+ pm->b2 = *py * *py;
+
+ ++px; ++py; ++pm;
+ }
+
+ return m;
+}
+
+struct mat2 *
+calc_window_sum(struct mat2 *m, int width, int height, int wsize)
+{
+ struct mat2 *avg, *v, *r;
+ float w;
+ int x, y, i, j;
+
+ avg = calloc(width * height, sizeof *avg);
+ if (!avg)
+ return NULL;
+
+ r = avg;
+ for (y = 0; y < height; ++y) {
+ for (x = 0; x < width; ++x) {
+ for (i = -wsize/2; i < wsize/2; ++i) {
+ for (j = -wsize/2; j < wsize/2; ++j) {
+ v = &m[(CLAMP(y+i, 0, height-1) * width
+ + CLAMP(x+j, 0, width-1))];
+ w = (1.0 / (2 * 3.14 * 0.16) *
+ exp(- i*i - j*j / 0.16));
+
+ r->a1 += w * v->a1;
+ r->a2 += w * v->a2;
+ r->b1 += w * v->b1;
+ r->b2 += w * v->b2;
+ }
+ }
+ ++r;
+ }
+ }
+
+ return avg;
+}
+
+gboolean
+check_neighbours(struct mat2 *m, int x, int y, int width, int height)
+{
+ int i, j;
+ gboolean max = TRUE;
+
+ for (j = MAX(0, y-1); j < MIN(y+1, height-1); ++j) {
+ for (i = MAX(0, x-1); i < MIN(x+1, width-1); ++i) {
+ if (m[j * width + i].mc > m[y * width + x].mc)
+ max = FALSE;
+ }
+ }
+
+ return max;
+}
+
+int
+main(int argc, char *argv[])
+{
+ GdkPixbuf *image, *grey;
+ int *deriv_x, *deriv_y;
+ gint sobel_x[] = {
+ 1, 0, -1,
+ 2, 0, -2,
+ 1, 0, -1
+ };
+ gint sobel_y[] = {
+ 1, 2, 1,
+ 0, 0, 0,
+ -1, -2, -1
+ };
+ const float k = 0.04;
+ int x, y, width, height, size, nch, stride;
+ struct mat2 *m, *n, *c;
+ guchar *p, *row;
+ float max_mc, threshold;
+
+ if (argc < 2)
+ return 1;
+
+ g_type_init();
+ image = gdk_pixbuf_new_from_file(argv[1], NULL);
+ if (!image)
+ return 1;
+ width = gdk_pixbuf_get_width(image);
+ height = gdk_pixbuf_get_height(image);
+
+ grey = gdk_pixbuf_copy(image);
+ grey_scale(grey);
+
+ deriv_x = conv(grey, sobel_x, 3);
+ deriv_y = conv(grey, sobel_y, 3);
+ gdk_pixbuf_save(grey, argc > 3 ? argv[3] : "grey.tiff", "tiff",
+ NULL, NULL);
+
+ m = multiply(deriv_x, deriv_y, width, height);
+ n = calc_window_sum(m, width, height, 9);
+ free(m);
+
+ max_mc = 0;
+ size = width * height;
+ for (c = n; c < n+size; ++c) {
+ c->mc = det(c) - k * trace(c) * trace(c);
+ if (c->mc > max_mc)
+ max_mc = c->mc;
+ }
+ printf("max_mc: %f\n", max_mc);
+
+ threshold = 0.0001 * max_mc;
+ pixbuf_get(image, &row, &width, &height, &nch, &stride);
+ for (y = 0; y < height; ++y, row += stride) {
+ for (x = 0, p = row; x < width; ++x, p += nch) {
+ if (n[y * width + x].mc > threshold &&
+ check_neighbours(n, x, y, width, height)) {
+ p[0] = 255;
+ p[1] = 0;
+ p[2] = 0;
+ printf("corner at: %d, %d\n", x, y);
+ }
+ }
+ }
+
+ gdk_pixbuf_save(image, argc > 2 ? argv[2] : "harris.tiff", "tiff",
+ NULL, NULL);
+
+ free(n);
+ free(deriv_x);
+ free(deriv_y);
+ g_object_unref(image);
+ g_object_unref(grey);
+
+ return 0;
+}