BUG Fix bounds in sum_rect()

Without this fix, it was possible to trigger a crash from the
interpreter, which, even if it was an edge case, is always a serious
bug.

closes #58

mahotas/features/_surf.cpp

@@ -39,8 +39,8 @@ template <typename T>
 double sum_rect(numpy::aligned_array<T> integral, int y0, int x0, int y1, int x1) {
     y0 = std::max<int>(y0-1, 0);
     x0 = std::max<int>(x0-1, 0);
-    y1 = std::min<int>(y1-1, integral.dim(0));
-    x1 = std::min<int>(x1-1, integral.dim(1));
+    y1 = std::min<int>(y1-1, integral.dim(0) - 1);
+    x1 = std::min<int>(x1-1, integral.dim(1) - 1);
 
     const T A = integral.at(y0,x0);
     const T B = integral.at(y0,x1);

mahotas/tests/test_surf.py

@@ -22,7 +22,7 @@ def test_integral2():
 
 def test_sum_rect():
     f = np.arange(800*160).reshape((800,160)) % 7
-    fi = surf.integral(f.copy()) 
+    fi = surf.integral(f.copy())
 
     np.random.seed(22)
     for i in range(100):
@@ -32,6 +32,13 @@ def test_sum_rect():
         x1 = np.random.randint(x0+1, 159)
         assert _surf.sum_rect(fi, y0, x0, y1, x1) == f[y0:y1, x0:x1].sum()
 
+def test_sum_rect_edge():
+    # regression
+    # https://github.com/luispedro/mahotas/issues/58
+    f = np.arange(80*60).reshape((80,60)) % 7
+    fi = surf.integral(f.copy())
+    _surf.sum_rect(fi, 0, 0, 81, 61)
+
 def test_surf_guassians():
     f = np.zeros((1024,1024))
     Y,X = np.indices(f.shape)