From faefbf93bc91a9fad25bf015d3e2e47b05a35199 Mon Sep 17 00:00:00 2001
From: Rostislav Vasilikhin <savuor@gmail.com>
Date: Fri, 16 Dec 2016 14:48:58 +0400
Subject: [PATCH] Merge pull request #7793 from savuor:openvx_pyrDown

OpenVX pyrDown wrappers (#7793)

* wrappers for vx_pyramid added

* initial version of pyrDown() wrapper added

* disabled for Khronos

* rewritten for new macro use; border mode added to node
---
 modules/imgproc/src/pyramids.cpp | 81 ++++++++++++++++++++++++++++++++
 1 file changed, 81 insertions(+)

diff --git a/modules/imgproc/src/pyramids.cpp b/modules/imgproc/src/pyramids.cpp
index d774396509..866a17f8eb 100644
--- a/modules/imgproc/src/pyramids.cpp
+++ b/modules/imgproc/src/pyramids.cpp
@@ -44,6 +44,8 @@
 #include "precomp.hpp"
 #include "opencl_kernels_imgproc.hpp"
 
+#include "opencv2/core/openvx/ovx_defs.hpp"
+
 namespace cv
 {
 
@@ -1254,6 +1256,82 @@ static bool ipp_pyrdown( InputArray _src, OutputArray _dst, const Size& _dsz, in
 }
 #endif
 
+#ifdef HAVE_OPENVX
+namespace cv
+{
+static bool openvx_pyrDown( InputArray _src, OutputArray _dst, const Size& _dsz, int borderType )
+{
+    using namespace ivx;
+
+    Mat srcMat = _src.getMat();
+
+    CV_Assert(!srcMat.empty());
+
+    Size ssize = _src.size();
+    Size acceptableSize = Size((ssize.width + 1) / 2, (ssize.height + 1) / 2);
+
+    // OpenVX limitations
+    if((srcMat.type() != CV_8U) ||
+       (borderType != BORDER_REPLICATE) ||
+       (_dsz != acceptableSize && _dsz.area() != 0))
+        return false;
+
+    // The only border mode which is supported by both cv::pyrDown() and OpenVX
+    // and produces predictable results
+    vx_border_t borderMode;
+    borderMode.mode = VX_BORDER_REPLICATE;
+
+    _dst.create( acceptableSize, srcMat.type() );
+    Mat dstMat = _dst.getMat();
+
+    CV_Assert( ssize.width > 0 && ssize.height > 0 &&
+            std::abs(acceptableSize.width*2 - ssize.width) <= 2 &&
+            std::abs(acceptableSize.height*2 - ssize.height) <= 2 );
+
+    try
+    {
+        Context context = Context::create();
+        if(context.vendorID() == VX_ID_KHRONOS)
+        {
+            // This implementation performs floor-like rounding
+            // (OpenCV uses floor(x+0.5)-like rounding)
+            // and ignores border mode (and loses 1px size border)
+            return false;
+        }
+
+        Image srcImg = Image::createFromHandle(context, Image::matTypeToFormat(srcMat.type()),
+                                               Image::createAddressing(srcMat), (void*)srcMat.data);
+        Image dstImg = Image::createFromHandle(context, Image::matTypeToFormat(dstMat.type()),
+                                               Image::createAddressing(dstMat), (void*)dstMat.data);
+
+        ivx::Scalar kernelSize = ivx::Scalar::create<VX_TYPE_INT32>(context, 5);
+        Graph graph = Graph::create(context);
+        ivx::Node halfNode = ivx::Node::create(graph, VX_KERNEL_HALFSCALE_GAUSSIAN, srcImg, dstImg, kernelSize);
+        halfNode.setBorder(borderMode);
+        graph.verify();
+        graph.process();
+
+#ifdef VX_VERSION_1_1
+        //we should take user memory back before release
+        //(it's not done automatically according to standard)
+        srcImg.swapHandle(); dstImg.swapHandle();
+#endif
+    }
+    catch (RuntimeError & e)
+    {
+        VX_DbgThrow(e.what());
+    }
+    catch (WrapperError & e)
+    {
+        VX_DbgThrow(e.what());
+    }
+
+    return true;
+}
+
+}
+#endif
+
 void cv::pyrDown( InputArray _src, OutputArray _dst, const Size& _dsz, int borderType )
 {
     CV_INSTRUMENT_REGION()
@@ -1263,6 +1341,9 @@ void cv::pyrDown( InputArray _src, OutputArray _dst, const Size& _dsz, int borde
     CV_OCL_RUN(_src.dims() <= 2 && _dst.isUMat(),
                ocl_pyrDown(_src, _dst, _dsz, borderType))
 
+    CV_OVX_RUN(_src.dims() <= 2,
+               openvx_pyrDown(_src, _dst, _dsz, borderType))
+
     Mat src = _src.getMat();
     Size dsz = _dsz.area() == 0 ? Size((src.cols + 1)/2, (src.rows + 1)/2) : _dsz;
     _dst.create( dsz, src.type() );