several fixes in gpu module

fixed iterations>1 case in morphological operations
fixed possible access violation in HSV2RGB
fixed the case learningRate==0 in BackgroundSubtractorMOG2

modules/gpu/src/bgfg_mog.cpp

@@ -251,7 +251,6 @@ void cv::gpu::MOG2_GPU::operator()(const GpuMat& frame, GpuMat& fgmask, float le
     learningRate = learningRate >= 0.0f && nframes_ > 1 ? learningRate : 1.0f / std::min(2 * nframes_, history);
     CV_Assert(learningRate >= 0.0f);
 
-    if (learningRate > 0.0f)
     mog2_gpu(frame, frame.channels(), fgmask, bgmodelUsedModes_, weight_, variance_, mean_, learningRate, -learningRate * fCT, bShadowDetection, StreamAccessor::getStream(stream));
 }
 

modules/gpu/src/filtering.cpp

@@ -576,8 +576,10 @@ namespace
         else if (iterations > 1 && countNonZero(_kernel) == _kernel.rows * _kernel.cols)
         {
             anchor = Point(anchor.x * iterations, anchor.y * iterations);
-            kernel = getStructuringElement(MORPH_RECT, Size(ksize.width + iterations * (ksize.width - 1),
-                ksize.height + iterations * (ksize.height - 1)), anchor);
+            kernel = getStructuringElement(MORPH_RECT,
+                                           Size(ksize.width + (iterations - 1) * (ksize.width - 1),
+                                                ksize.height + (iterations - 1) * (ksize.height - 1)),
+                                           anchor);
             iterations = 1;
         }
         else

modules/gpu/src/opencv2/gpu/device/detail/color_detail.hpp

@@ -1140,6 +1140,12 @@ namespace cv { namespace gpu { namespace device
                 int sector = __float2int_rd(h);
                 h -= sector;
 
+                if ( (unsigned)sector >= 6u )
+                {
+                    sector = 0;
+                    h = 0.f;
+                }
+
                 float tab[4];
                 tab[0] = v;
                 tab[1] = v * (1.f - s);

modules/imgproc/src/generalized_hough.cpp

@@ -64,10 +64,6 @@ namespace
     {
         return fabs(v) > numeric_limits<float>::epsilon();
     }
-    /*bool notNull(double v)
-    {
-        return fabs(v) > numeric_limits<double>::epsilon();
-    }*/
 
     class GHT_Pos : public GeneralizedHough
     {