Fix multichannel warping with BORDER_CONSTANT

Warping a matrix with more than 4 channels using BORDER_CONSTANT and
INTER_NEAREST, INTER_CUBIC or INTER_LANCZOS4 interpolation led to
undefined behaviour. This commit changes the behavior of these methods
to be similar to that of INTER_LINEAR. Changed the scope of some of the
variables to more local. Modified some tests to be able to detect the
error described.

diff --git a/modules/imgproc/src/imgwarp.cpp b/modules/imgproc/src/imgwarp.cpp
index 7bcf16a..c5d2182 100644 (file)
--- a/modules/imgproc/src/imgwarp.cpp
+++ b/modules/imgproc/src/imgwarp.cpp
@@ -3533,14 +3533,13 @@ static void remapNearest( const Mat& _src, Mat& _dst, const Mat& _xy,
                           int borderType, const Scalar& _borderValue )
 {
     Size ssize = _src.size(), dsize = _dst.size();
-    int cn = _src.channels();
+    const int cn = _src.channels();
     const T* S0 = _src.ptr<T>();
+    T cval[CV_CN_MAX];
     size_t sstep = _src.step/sizeof(S0[0]);
-    Scalar_<T> cval(saturate_cast<T>(_borderValue[0]),
-        saturate_cast<T>(_borderValue[1]),
-        saturate_cast<T>(_borderValue[2]),
-        saturate_cast<T>(_borderValue[3]));
-    int dx, dy;
+
+    for(int k = 0; k < cn; k++ )
+        cval[k] = saturate_cast<T>(_borderValue[k & 3]);
 
     unsigned width1 = ssize.width, height1 = ssize.height;
 
@@ -3550,14 +3549,14 @@ static void remapNearest( const Mat& _src, Mat& _dst, const Mat& _xy,
         dsize.height = 1;
     }
 
-    for( dy = 0; dy < dsize.height; dy++ )
+    for(int dy = 0; dy < dsize.height; dy++ )
     {
         T* D = _dst.ptr<T>(dy);
         const short* XY = _xy.ptr<short>(dy);
 
         if( cn == 1 )
         {
-            for( dx = 0; dx < dsize.width; dx++ )
+            for(int dx = 0; dx < dsize.width; dx++ )
             {
                 int sx = XY[dx*2], sy = XY[dx*2+1];
                 if( (unsigned)sx < width1 && (unsigned)sy < height1 )
@@ -3583,9 +3582,9 @@ static void remapNearest( const Mat& _src, Mat& _dst, const Mat& _xy,
         }
         else
         {
-            for( dx = 0; dx < dsize.width; dx++, D += cn )
+            for(int dx = 0; dx < dsize.width; dx++, D += cn )
             {
-                int sx = XY[dx*2], sy = XY[dx*2+1], k;
+                int sx = XY[dx*2], sy = XY[dx*2+1];
                 const T *S;
                 if( (unsigned)sx < width1 && (unsigned)sy < height1 )
                 {
@@ -3602,7 +3601,7 @@ static void remapNearest( const Mat& _src, Mat& _dst, const Mat& _xy,
                     else
                     {
                         S = S0 + sy*sstep + sx*cn;
-                        for( k = 0; k < cn; k++ )
+                        for(int k = 0; k < cn; k++ )
                             D[k] = S[k];
                     }
                 }
@@ -3622,7 +3621,7 @@ static void remapNearest( const Mat& _src, Mat& _dst, const Mat& _xy,
                         sy = borderInterpolate(sy, ssize.height, borderType);
                         S = S0 + sy*sstep + sx*cn;
                     }
-                    for( k = 0; k < cn; k++ )
+                    for(int k = 0; k < cn; k++ )
                         D[k] = S[k];
                 }
             }
@@ -3852,16 +3851,15 @@ static void remapBilinear( const Mat& _src, Mat& _dst, const Mat& _xy,
     typedef typename CastOp::rtype T;
     typedef typename CastOp::type1 WT;
     Size ssize = _src.size(), dsize = _dst.size();
-    int k, cn = _src.channels();
+    const int cn = _src.channels();
     const AT* wtab = (const AT*)_wtab;
     const T* S0 = _src.ptr<T>();
     size_t sstep = _src.step/sizeof(S0[0]);
     T cval[CV_CN_MAX];
-    int dx, dy;
     CastOp castOp;
     VecOp vecOp;
 
-    for( k = 0; k < cn; k++ )
+    for(int k = 0; k < cn; k++ )
         cval[k] = saturate_cast<T>(_borderValue[k & 3]);
 
     unsigned width1 = std::max(ssize.width-1, 0), height1 = std::max(ssize.height-1, 0);
@@ -3871,7 +3869,7 @@ static void remapBilinear( const Mat& _src, Mat& _dst, const Mat& _xy,
         width1 = std::max(ssize.width-2, 0);
 #endif
 
-    for( dy = 0; dy < dsize.height; dy++ )
+    for(int dy = 0; dy < dsize.height; dy++ )
     {
         T* D = _dst.ptr<T>(dy);
         const short* XY = _xy.ptr<short>(dy);
@@ -3879,7 +3877,7 @@ static void remapBilinear( const Mat& _src, Mat& _dst, const Mat& _xy,
         int X0 = 0;
         bool prevInlier = false;
 
-        for( dx = 0; dx <= dsize.width; dx++ )
+        for(int dx = 0; dx <= dsize.width; dx++ )
         {
             bool curInlier = dx < dsize.width ?
                 (unsigned)XY[dx*2] < width1 &&
@@ -3948,7 +3946,7 @@ static void remapBilinear( const Mat& _src, Mat& _dst, const Mat& _xy,
                         int sx = XY[dx*2], sy = XY[dx*2+1];
                         const AT* w = wtab + FXY[dx]*4;
                         const T* S = S0 + sy*sstep + sx*cn;
-                        for( k = 0; k < cn; k++ )
+                        for(int k = 0; k < cn; k++ )
                         {
                             WT t0 = S[k]*w[0] + S[k+cn]*w[1] + S[sstep+k]*w[2] + S[sstep+k+cn]*w[3];
                             D[k] = castOp(t0);
@@ -4012,7 +4010,7 @@ static void remapBilinear( const Mat& _src, Mat& _dst, const Mat& _xy,
                             (sx >= ssize.width || sx+1 < 0 ||
                              sy >= ssize.height || sy+1 < 0) )
                         {
-                            for( k = 0; k < cn; k++ )
+                            for(int k = 0; k < cn; k++ )
                                 D[k] = cval[k];
                         }
                         else
@@ -4046,7 +4044,7 @@ static void remapBilinear( const Mat& _src, Mat& _dst, const Mat& _xy,
                                 v2 = sx0 >= 0 && sy1 >= 0 ? S0 + sy1*sstep + sx0*cn : &cval[0];
                                 v3 = sx1 >= 0 && sy1 >= 0 ? S0 + sy1*sstep + sx1*cn : &cval[0];
                             }
-                            for( k = 0; k < cn; k++ )
+                            for(int k = 0; k < cn; k++ )
                                 D[k] = castOp(WT(v0[k]*w[0] + v1[k]*w[1] + v2[k]*w[2] + v3[k]*w[3]));
                         }
                     }
@@ -4064,16 +4062,16 @@ static void remapBicubic( const Mat& _src, Mat& _dst, const Mat& _xy,
     typedef typename CastOp::rtype T;
     typedef typename CastOp::type1 WT;
     Size ssize = _src.size(), dsize = _dst.size();
-    int cn = _src.channels();
+    const int cn = _src.channels();
     const AT* wtab = (const AT*)_wtab;
     const T* S0 = _src.ptr<T>();
     size_t sstep = _src.step/sizeof(S0[0]);
-    Scalar_<T> cval(saturate_cast<T>(_borderValue[0]),
-        saturate_cast<T>(_borderValue[1]),
-        saturate_cast<T>(_borderValue[2]),
-        saturate_cast<T>(_borderValue[3]));
-    int dx, dy;
+    T cval[CV_CN_MAX];
     CastOp castOp;
+
+    for(int k = 0; k < cn; k++ )
+        cval[k] = saturate_cast<T>(_borderValue[k & 3]);
+
     int borderType1 = borderType != BORDER_TRANSPARENT ? borderType : BORDER_REFLECT_101;
 
     unsigned width1 = std::max(ssize.width-3, 0), height1 = std::max(ssize.height-3, 0);
@@ -4084,21 +4082,20 @@ static void remapBicubic( const Mat& _src, Mat& _dst, const Mat& _xy,
         dsize.height = 1;
     }
 
-    for( dy = 0; dy < dsize.height; dy++ )
+    for(int dy = 0; dy < dsize.height; dy++ )
     {
         T* D = _dst.ptr<T>(dy);
         const short* XY = _xy.ptr<short>(dy);
         const ushort* FXY = _fxy.ptr<ushort>(dy);
 
-        for( dx = 0; dx < dsize.width; dx++, D += cn )
+        for(int dx = 0; dx < dsize.width; dx++, D += cn )
         {
             int sx = XY[dx*2]-1, sy = XY[dx*2+1]-1;
             const AT* w = wtab + FXY[dx]*16;
-            int i, k;
             if( (unsigned)sx < width1 && (unsigned)sy < height1 )
             {
                 const T* S = S0 + sy*sstep + sx*cn;
-                for( k = 0; k < cn; k++ )
+                for(int k = 0; k < cn; k++ )
                 {
                     WT sum = S[0]*w[0] + S[cn]*w[1] + S[cn*2]*w[2] + S[cn*3]*w[3];
                     S += sstep;
@@ -4123,21 +4120,21 @@ static void remapBicubic( const Mat& _src, Mat& _dst, const Mat& _xy,
                     (sx >= ssize.width || sx+4 <= 0 ||
                     sy >= ssize.height || sy+4 <= 0))
                 {
-                    for( k = 0; k < cn; k++ )
+                    for(int k = 0; k < cn; k++ )
                         D[k] = cval[k];
                     continue;
                 }
 
-                for( i = 0; i < 4; i++ )
+                for(int i = 0; i < 4; i++ )
                 {
                     x[i] = borderInterpolate(sx + i, ssize.width, borderType1)*cn;
                     y[i] = borderInterpolate(sy + i, ssize.height, borderType1);
                 }
 
-                for( k = 0; k < cn; k++, S0++, w -= 16 )
+                for(int k = 0; k < cn; k++, S0++, w -= 16 )
                 {
                     WT cv = cval[k], sum = cv*ONE;
-                    for( i = 0; i < 4; i++, w += 4 )
+                    for(int i = 0; i < 4; i++, w += 4 )
                     {
                         int yi = y[i];
                         const T* S = S0 + yi*sstep;
@@ -4169,16 +4166,16 @@ static void remapLanczos4( const Mat& _src, Mat& _dst, const Mat& _xy,
     typedef typename CastOp::rtype T;
     typedef typename CastOp::type1 WT;
     Size ssize = _src.size(), dsize = _dst.size();
-    int cn = _src.channels();
+    const int cn = _src.channels();
     const AT* wtab = (const AT*)_wtab;
     const T* S0 = _src.ptr<T>();
     size_t sstep = _src.step/sizeof(S0[0]);
-    Scalar_<T> cval(saturate_cast<T>(_borderValue[0]),
-        saturate_cast<T>(_borderValue[1]),
-        saturate_cast<T>(_borderValue[2]),
-        saturate_cast<T>(_borderValue[3]));
-    int dx, dy;
+    T cval[CV_CN_MAX];
     CastOp castOp;
+
+    for(int k = 0; k < cn; k++ )
+        cval[k] = saturate_cast<T>(_borderValue[k & 3]);
+
     int borderType1 = borderType != BORDER_TRANSPARENT ? borderType : BORDER_REFLECT_101;
 
     unsigned width1 = std::max(ssize.width-7, 0), height1 = std::max(ssize.height-7, 0);
@@ -4189,21 +4186,20 @@ static void remapLanczos4( const Mat& _src, Mat& _dst, const Mat& _xy,
         dsize.height = 1;
     }
 
-    for( dy = 0; dy < dsize.height; dy++ )
+    for(int dy = 0; dy < dsize.height; dy++ )
     {
         T* D = _dst.ptr<T>(dy);
         const short* XY = _xy.ptr<short>(dy);
         const ushort* FXY = _fxy.ptr<ushort>(dy);
 
-        for( dx = 0; dx < dsize.width; dx++, D += cn )
+        for(int dx = 0; dx < dsize.width; dx++, D += cn )
         {
             int sx = XY[dx*2]-3, sy = XY[dx*2+1]-3;
             const AT* w = wtab + FXY[dx]*64;
             const T* S = S0 + sy*sstep + sx*cn;
-            int i, k;
             if( (unsigned)sx < width1 && (unsigned)sy < height1 )
             {
-                for( k = 0; k < cn; k++ )
+                for(int k = 0; k < cn; k++ )
                 {
                     WT sum = 0;
                     for( int r = 0; r < 8; r++, S += sstep, w += 8 )
@@ -4226,21 +4222,21 @@ static void remapLanczos4( const Mat& _src, Mat& _dst, const Mat& _xy,
                     (sx >= ssize.width || sx+8 <= 0 ||
                     sy >= ssize.height || sy+8 <= 0))
                 {
-                    for( k = 0; k < cn; k++ )
+                    for(int k = 0; k < cn; k++ )
                         D[k] = cval[k];
                     continue;
                 }
 
-                for( i = 0; i < 8; i++ )
+                for(int i = 0; i < 8; i++ )
                 {
                     x[i] = borderInterpolate(sx + i, ssize.width, borderType1)*cn;
                     y[i] = borderInterpolate(sy + i, ssize.height, borderType1);
                 }
 
-                for( k = 0; k < cn; k++, S0++, w -= 64 )
+                for(int k = 0; k < cn; k++, S0++, w -= 64 )
                 {
                     WT cv = cval[k], sum = cv*ONE;
-                    for( i = 0; i < 8; i++, w += 8 )
+                    for(int i = 0; i < 8; i++, w += 8 )
                     {
                         int yi = y[i];
                         const T* S1 = S0 + yi*sstep;

diff --git a/modules/imgproc/test/test_imgwarp.cpp b/modules/imgproc/test/test_imgwarp.cpp
index 8246754..8d7b1f8 100644 (file)
--- a/modules/imgproc/test/test_imgwarp.cpp
+++ b/modules/imgproc/test/test_imgwarp.cpp
@@ -1686,22 +1686,33 @@ TEST(Resize, Area_half)
 
 TEST(Imgproc_Warp, multichannel)
 {
+    static const int inter_types[] = {INTER_NEAREST, INTER_AREA, INTER_CUBIC,
+                                      INTER_LANCZOS4, INTER_LINEAR};
+    static const int inter_n = sizeof(inter_types) / sizeof(int);
+
+    static const int border_types[] = {BORDER_CONSTANT, BORDER_DEFAULT,
+                                       BORDER_REFLECT, BORDER_REPLICATE,
+                                       BORDER_WRAP, BORDER_WRAP};
+    static const int border_n = sizeof(border_types) / sizeof(int);
+
     RNG& rng = theRNG();
-    for( int iter = 0; iter < 30; iter++ )
+    for( int iter = 0; iter < 100; iter++ )
     {
+        int inter = inter_types[rng.uniform(0, inter_n)];
+        int border = border_types[rng.uniform(0, border_n)];
         int width = rng.uniform(3, 333);
         int height = rng.uniform(3, 333);
-        int cn = rng.uniform(1, 10);
+        int cn = rng.uniform(1, 15);
         Mat src(height, width, CV_8UC(cn)), dst;
         //randu(src, 0, 256);
         src.setTo(0.);
 
-        Mat rot = getRotationMatrix2D(Point2f(0.f, 0.f), 1, 1);
-        warpAffine(src, dst, rot, src.size());
+        Mat rot = getRotationMatrix2D(Point2f(0.f, 0.f), 1.0, 1.0);
+        warpAffine(src, dst, rot, src.size(), inter, border);
         ASSERT_EQ(0.0, norm(dst, NORM_INF));
         Mat rot2 = Mat::eye(3, 3, rot.type());
         rot.copyTo(rot2.rowRange(0, 2));
-        warpPerspective(src, dst, rot2, src.size());
+        warpPerspective(src, dst, rot2, src.size(), inter, border);
         ASSERT_EQ(0.0, norm(dst, NORM_INF));
     }
 }