Merge pull request #3777 from ilya-lavrenov:nvidia_cvtcolor_eps

modules/core/include/opencv2/core/ocl.hpp

@@ -184,6 +184,7 @@ public:
     // After fix restore code in arithm.cpp: ocl_compare()
     inline bool isAMD() const { return vendorID() == VENDOR_AMD; }
     inline bool isIntel() const { return vendorID() == VENDOR_INTEL; }
+    inline bool isNVidia() const { return vendorID() == VENDOR_NVIDIA; }
 
     int maxClockFrequency() const;
     int maxComputeUnits() const;

modules/imgproc/test/ocl/test_color.cpp

@@ -128,7 +128,7 @@ OCL_TEST_P(CvtColor, BGR2GRAY) { performTest(3, 1, CVTCODE(BGR2GRAY)); }
 OCL_TEST_P(CvtColor, GRAY2BGR) { performTest(1, 3, CVTCODE(GRAY2BGR)); }
 OCL_TEST_P(CvtColor, RGBA2GRAY) { performTest(4, 1, CVTCODE(RGBA2GRAY)); }
 OCL_TEST_P(CvtColor, GRAY2RGBA) { performTest(1, 4, CVTCODE(GRAY2RGBA)); }
-OCL_TEST_P(CvtColor, BGRA2GRAY) { performTest(4, 1, CVTCODE(BGRA2GRAY)); }
+OCL_TEST_P(CvtColor, BGRA2GRAY) { performTest(4, 1, CVTCODE(BGRA2GRAY), cv::ocl::Device::getDefault().isNVidia() ? 1 : 1e-3); }
 OCL_TEST_P(CvtColor, GRAY2BGRA) { performTest(1, 4, CVTCODE(GRAY2BGRA)); }
 
 // RGB <-> YUV