spatialGradient: Re-introduce 2-rows at a time

modules/imgproc/src/spatialgradient.cpp

@@ -130,13 +130,16 @@ void spatialGradient( InputArray _src, OutputArray _dx, OutputArray _dy,
     v_int16x8 v_s1m1, v_s1m2, v_s1n1, v_s1n2, v_s1p1, v_s1p2,
               v_s2m1, v_s2m2, v_s2n1, v_s2n2, v_s2p1, v_s2p2,
               v_s3m1, v_s3m2, v_s3n1, v_s3n2, v_s3p1, v_s3p2,
-              v_tmp,  v_sdx, v_sdy;
+              v_s4m1, v_s4m2, v_s4n1, v_s4n2, v_s4p1, v_s4p2,
+              v_tmp,  v_sdx1, v_sdx2, v_sdy1, v_sdy2;
 
-    for ( i = 0; i < H - 2; i += 2 )
+    uchar *m_src;
+    short *n_dx, *n_dy;
+
+    for ( i = 0; i < H - 1; i += 2 )
     {
-        p_src = P_src[i]; c_src = P_src[i+1]; n_src = P_src[i+2];
-        c_dx = P_dx [i];
-        c_dy = P_dy [i];
+        p_src = P_src[i]; c_src = P_src[i+1]; n_src = P_src[i+2]; m_src = P_src[i+3];
+        c_dx = P_dx[i]; c_dy = P_dy[i]; n_dx = P_dx[i+1]; n_dy = P_dy[i+1];
 
         // 16-column chunks at a time
         for ( j = 0; j < W - 15; j += 16 )
@@ -208,23 +211,62 @@ void spatialGradient( InputArray _src, OutputArray _dx, OutputArray _dy,
             v_s3p1 = v_reinterpret_as_s16(v_up1);
             v_s3p2 = v_reinterpret_as_s16(v_up2);
 
+            // Load fourth row for 3x3 Sobel filter
+            if ( left ) { tmp = m_src[j-1]; m_src[j-1] = m_src[j+j_offl]; }
+            v_um = v_load(&m_src[j-1]);
+            if ( left ) m_src[j-1] = tmp;
+
+            v_un = v_load(&m_src[j]);
+
+            if ( right ) { tmp = m_src[j+16]; m_src[j+16] = m_src[j+15+j_offr]; }
+            v_up = v_load(&m_src[j+1]);
+            if ( right ) m_src[j+16] = tmp;
+
+            v_expand(v_um, v_um1, v_um2);
+            v_expand(v_un, v_un1, v_un2);
+            v_expand(v_up, v_up1, v_up2);
+            v_s4m1 = v_reinterpret_as_s16(v_um1);
+            v_s4m2 = v_reinterpret_as_s16(v_um2);
+            v_s4n1 = v_reinterpret_as_s16(v_un1);
+            v_s4n2 = v_reinterpret_as_s16(v_un2);
+            v_s4p1 = v_reinterpret_as_s16(v_up1);
+            v_s4p2 = v_reinterpret_as_s16(v_up2);
+
             // dx
             v_tmp = v_s2p1 - v_s2m1;
-            v_sdx = (v_s1p1 - v_s1m1) + (v_tmp + v_tmp) + (v_s3p1 - v_s3m1);
+            v_sdx1 = (v_s1p1 - v_s1m1) + (v_tmp + v_tmp) + (v_s3p1 - v_s3m1);
             v_tmp = v_s2p2 - v_s2m2;
-            v_sdx = (v_s1p2 - v_s1m2) + (v_tmp + v_tmp) + (v_s3p2 - v_s3m2);
+            v_sdx2 = (v_s1p2 - v_s1m2) + (v_tmp + v_tmp) + (v_s3p2 - v_s3m2);
 
             // dy
             v_tmp = v_s3n1 - v_s1n1;
-            v_sdy = (v_s3m1 - v_s1m1) + (v_tmp + v_tmp) + (v_s3p1 - v_s1p1);
+            v_sdy1 = (v_s3m1 - v_s1m1) + (v_tmp + v_tmp) + (v_s3p1 - v_s1p1);
             v_tmp = v_s3n2 - v_s1n2;
-            v_sdy = (v_s3m2 - v_s1m2) + (v_tmp + v_tmp) + (v_s3p2 - v_s1p2);
+            v_sdy2 = (v_s3m2 - v_s1m2) + (v_tmp + v_tmp) + (v_s3p2 - v_s1p2);
+
+            // Store
+            v_store(&c_dx[j],   v_sdx1);
+            v_store(&c_dx[j+8], v_sdx2);
+            v_store(&c_dy[j],   v_sdy1);
+            v_store(&c_dy[j+8], v_sdy2);
+
+            // dx
+            v_tmp = v_s3p1 - v_s3m1;
+            v_sdx1 = (v_s2p1 - v_s2m1) + (v_tmp + v_tmp) + (v_s4p1 - v_s4m1);
+            v_tmp = v_s3p2 - v_s3m2;
+            v_sdx2 = (v_s2p2 - v_s2m2) + (v_tmp + v_tmp) + (v_s4p2 - v_s4m2);
+
+            // dy
+            v_tmp = v_s4n1 - v_s2n1;
+            v_sdy1 = (v_s4m1 - v_s2m1) + (v_tmp + v_tmp) + (v_s4p1 - v_s2p1);
+            v_tmp = v_s4n2 - v_s2n2;
+            v_sdy2 = (v_s4m2 - v_s2m2) + (v_tmp + v_tmp) + (v_s4p2 - v_s2p2);
 
             // Store
-            v_store(&c_dx[j],   v_sdx);
-            v_store(&c_dx[j+8], v_sdx);
-            v_store(&c_dy[j],   v_sdy);
-            v_store(&c_dy[j+8], v_sdy);
+            v_store(&n_dx[j],   v_sdx1);
+            v_store(&n_dx[j+8], v_sdx2);
+            v_store(&n_dy[j],   v_sdy1);
+            v_store(&n_dy[j+8], v_sdy2);
         }
     }
     i_start = i;