Fixing overflow of clear_connected_components where starting point is zero and direction is -1.

radixalgorithm/marchingsquares.i.hh

@@ -31,10 +31,10 @@ void MarchingSquares<data_type>::clear_connected_component(int row, int col,
     // search neighbors
     for (int direction = 0; direction < 4; ++direction)
     {
-      size_t nc = col + dx[direction];
-      size_t nr = row + dy[direction];
-      if (nc < 0 || nc == mColumns) continue;  // out of bounds
-      if (nr < 0 || nr == mRows) continue;     // out of bounds
+      int nc = col + dx[direction];
+      int nr = row + dy[direction];
+      if (nc < 0 || nc >= mColumns) continue;  // out of bounds
+      if (nr < 0 || nr >= mRows) continue;     // out of bounds
       size_t nc_i = mColumns * nr + nc;
       if (mBit[nc_i] == label)
       {