Merge pull request #2937 from scloke:patch-1

* Divide by zero error in SEEDS Superpixels #2935

When processing a large number of images, a program crash can occur with a divide by zero error in the above function. Changing the order of multiplication / division avoids a division by zero.

* Update seeds.cpp

Minor corrections

Author: scloke

modules/ximgproc/src/seeds.cpp

@@ -136,8 +136,8 @@ class SuperpixelSEEDSImpl : public SuperpixelSEEDS
     //compute initial label for sublevels: level <= seeds_top_level
     //this is an equally sized grid with size nr_h[level]*nr_w[level]
     int computeLabel(int level, int x, int y) {
-        return std::min(y / (height / nr_wh[2 * level + 1]), nr_wh[2 * level + 1] - 1) * nr_wh[2 * level]
-                + std::min((x / (width / nr_wh[2 * level])), nr_wh[2 * level] - 1);
+        return std::min(y * nr_wh[2 * level + 1] / height, nr_wh[2 * level + 1] - 1) * nr_wh[2 * level]
+            + std::min(x * nr_wh[2 * level] / width, nr_wh[2 * level] - 1);
     }
     inline int nrLabels(int level) const {
         return nr_wh[2 * level + 1] * nr_wh[2 * level];