Merge pull request #12777 from UnderscoreAsterisk:document-cvtColorTwoPlane

* Add documentation for cvtColorTwoPlane

* Change brief and add links

modules/imgproc/include/opencv2/imgproc.hpp

@@ -3636,6 +3636,24 @@ channels is derived automatically from src and code.
  */
 CV_EXPORTS_W void cvtColor( InputArray src, OutputArray dst, int code, int dstCn = 0 );
 
+/** @brief Converts an image from one color space to another where the source image is
+stored in two planes.
+
+This function only supports YUV420 to RGB conversion as of now.
+
+@param src1: 8-bit image (#CV_8U) of the Y plane.
+@param src2: image containing interleaved U/V plane.
+@param dst: output image.
+@param code: Specifies the type of conversion. It can take any of the following values:
+- #COLOR_YUV2BGR_NV12
+- #COLOR_YUV2RGB_NV12
+- #COLOR_YUV2BGRA_NV12
+- #COLOR_YUV2RGBA_NV12
+- #COLOR_YUV2BGR_NV21
+- #COLOR_YUV2RGB_NV21
+- #COLOR_YUV2BGRA_NV21
+- #COLOR_YUV2RGBA_NV21
+*/
 CV_EXPORTS_W void cvtColorTwoPlane( InputArray src1, InputArray src2, OutputArray dst, int code );
 
 //! @} imgproc_misc