pkg: remove version from include/libstick-0.1/

[libstick.git] / include / libstick / image.h

diff --git a/include/libstick/image.h b/include/libstick/image.h
new file mode 100644 (file)
index 0000000..abb1df0
--- /dev/null
+++ b/include/libstick/image.h
@@ -0,0 +1,86 @@
+#ifndef image_h_uiHiKahYooroomai
+#define image_h_uiHiKahYooroomai
+
+#include "simplicialcomplex.h"
+
+
+namespace libstick {
+
+/** We consider an image, i.e. a rectangular arrangement of pixels, of given
+ * height and width. Every pixel has a specific value (e.g., grey value) given
+ * by the 'values' array as concatenation of all rows. We add every pixel as
+ * vertex with its value as simplex value. We further triangulate the resulting
+ * rectangular latice as a grid graph together with south-west to north-east
+ * edges for each of the small squares of the grid graph. Finally the resulting
+ * triangles are added. For all non-vertex simplices the maximum of its
+ * vertex-values is used as its value. The first pixel is considered to be at
+ * bottom-left. */
+template<class VT, class IT>
+void add_image_to_complex(simplicial_complex<2, IT, VT> &s, const VT *values, size_t width, size_t height) {
+    // Add the vertices
+    const IT v1st = s.size();
+    for (unsigned i=0; i < height; ++i)
+        for (unsigned j=0; j < width; ++j)
+            s.add_simplex(0, NULL, values[i*width + j]);
+
+    //      row i+1 o-------o
+    //              |      /|
+    //              |     / |
+    //              |   2/  |
+    //            0 |   /   |
+    //              |  /    |
+    //              | /     |
+    //              |/  1   |
+    //        row i o-------o
+    //              ^
+    //           column j
+
+    IT faces[3];
+
+    // Adding horizontal edges
+    const IT he1st = s.size();
+    for (unsigned i=0; i < height; ++i)
+        for (unsigned j=0; j < width-1; ++j) {
+            faces[0] = v1st + i*width + j;
+            faces[1] = faces[0] + 1;
+            s.add_simplex(1, faces);
+        }
+
+    // Adding vertical edges
+    const IT ve1st = s.size();
+    for (unsigned i=0; i < height-1; ++i)
+        for (unsigned j=0; j < width; ++j) {
+            faces[0] = v1st + i*width + j;
+            faces[1] = faces[0] + width;
+            s.add_simplex(1, faces);
+        }
+
+    // Adding diagonal edges
+    const IT de1st = s.size();
+    for (unsigned i=0; i < height-1; ++i)
+        for (unsigned j=0; j < width-1; ++j) {
+            faces[0] = v1st + i*width + j;
+            faces[1] = faces[0] + width + 1;
+            s.add_simplex(1, faces);
+        }
+
+    // Add triangles
+    for (unsigned i=0; i < height-1; ++i)
+        for (unsigned j=0; j < width-1; ++j) {
+            faces[0] = he1st + i*(width-1) + j;
+            faces[1] = ve1st + i*width + j + 1;
+            faces[2] = de1st + i*(width-1) + j;
+            s.add_simplex(2, faces);
+
+            faces[0] = he1st + (i+1)*(width-1) + j;
+            faces[1] = ve1st + i*width + j;
+            faces[2] = de1st + i*(width-1) + j;
+            s.add_simplex(2, faces);
+        }
+}
+
+
+}
+
+#endif
+