Added multithreaded implementation for RGB to YUV420p color conversion

diff --git a/modules/imgproc/src/color.cpp b/modules/imgproc/src/color.cpp
index 82c2195..3799d43 100644 (file)
--- a/modules/imgproc/src/color.cpp
+++ b/modules/imgproc/src/color.cpp
@@ -2744,6 +2744,16 @@ const int ITUR_BT_601_CVG = -852492;
 const int ITUR_BT_601_CVR = 1673527;
 const int ITUR_BT_601_SHIFT = 20;
 
+// Coefficients for RGB to YUV420p conversion
+const int ITUR_BT_601_CRY =  269484;
+const int ITUR_BT_601_CGY =  528482;
+const int ITUR_BT_601_CBY =  102760;
+const int ITUR_BT_601_CRU = -155188;
+const int ITUR_BT_601_CGU = -305135;
+const int ITUR_BT_601_CBU =  460324;
+const int ITUR_BT_601_CGV = -385875;
+const int ITUR_BT_601_CBV = -74448;
+
 template<int bIdx, int uIdx>
 struct YUV420sp2RGB888Invoker
 {
@@ -3078,54 +3088,80 @@ inline void cvtYUV420p2RGBA(Mat& _dst, int _stride, const uchar* _y1, const ucha
 
 ///////////////////////////////////// RGB -> YUV420p /////////////////////////////////////
 
-template<int bIdx, int uIdx>
-static void cvtRGBtoYUV420p(const Mat& src, Mat& dst)
+template<int bIdx>
+struct RGB888toYUV420pInvoker: public ParallelLoopBody
 {
-    //const float coeffs[] = {  0.257f,  0.504f, 0.098f,
-    //                         -0.148f, -0.291f, 0.439f,
-    //                         -0.368f, -0.071f };
-    const int coeffs[] = {  269484,  528482, 102760,
-                           -155188, -305135, 460324,
-                           -385875, -74448 };
-
-    const int w = src.cols;
-    const int h = src.rows;
+    RGB888toYUV420pInvoker( const Mat& src, Mat* dst, const int uIdx )
+        : src_(src),
+          dst_(dst),
+          uIdx_(uIdx) { }
 
-    const int cn = src.channels();
-    for( int i = 0; i < h / 2; i++ )
+    void operator()(const Range& rowRange) const
     {
-        const uchar* row0 = src.ptr<uchar>(2*i);
-        const uchar* row1 = src.ptr<uchar>(2*i + 1);
-
-        uchar* y = dst.ptr<uchar>(2*i);
-        uchar* u = dst.ptr<uchar>(h + i/2) + (i % 2) * (w/2);
-        uchar* v = dst.ptr<uchar>(h + (i + h/2)/2) + ((i + h/2) % 2) * (w/2);
-        if( uIdx == 2 ) std::swap(u, v);
+        const int w = src_.cols;
+        const int h = src_.rows;
 
-        for( int j = 0, k = 0; j < w * cn; j += 2*cn, k++ )
+        const int cn = src_.channels();
+        for( int i = rowRange.start; i < rowRange.end; i++ )
         {
-            int r00 = row0[2-bIdx + j];      int g00 = row0[1 + j];      int b00 = row0[bIdx + j];
-            int r01 = row0[2-bIdx + cn + j]; int g01 = row0[1 + cn + j]; int b01 = row0[bIdx + cn + j];
-            int r10 = row1[2-bIdx + j];      int g10 = row1[1 + j];      int b10 = row1[bIdx + j];
-            int r11 = row1[2-bIdx + cn + j]; int g11 = row1[1 + cn + j]; int b11 = row1[bIdx + cn + j];
-            
-            int y00 = coeffs[0]*r00 + coeffs[1]*g00 + coeffs[2]*b00 + (1 << (ITUR_BT_601_SHIFT - 1)) + (16 << ITUR_BT_601_SHIFT);
-            int y01 = coeffs[0]*r01 + coeffs[1]*g01 + coeffs[2]*b01 + (1 << (ITUR_BT_601_SHIFT - 1)) + (16 << ITUR_BT_601_SHIFT);
-            int y10 = coeffs[0]*r10 + coeffs[1]*g10 + coeffs[2]*b10 + (1 << (ITUR_BT_601_SHIFT - 1)) + (16 << ITUR_BT_601_SHIFT);
-            int y11 = coeffs[0]*r11 + coeffs[1]*g11 + coeffs[2]*b11 + (1 << (ITUR_BT_601_SHIFT - 1)) + (16 << ITUR_BT_601_SHIFT);
-            
-            y[2*k + 0]            = saturate_cast<uchar>(y00 >> ITUR_BT_601_SHIFT);
-            y[2*k + 1]            = saturate_cast<uchar>(y01 >> ITUR_BT_601_SHIFT);
-            y[2*k + dst.step + 0] = saturate_cast<uchar>(y10 >> ITUR_BT_601_SHIFT);
-            y[2*k + dst.step + 1] = saturate_cast<uchar>(y11 >> ITUR_BT_601_SHIFT);
+            const uchar* row0 = src_.ptr<uchar>(2 * i);
+            const uchar* row1 = src_.ptr<uchar>(2 * i + 1);
 
-            int u00 = coeffs[3]*r00 + coeffs[4]*g00 + coeffs[5]*b00 + (1 << (ITUR_BT_601_SHIFT - 1)) + (128 << ITUR_BT_601_SHIFT);
-            int v00 = coeffs[5]*r00 + coeffs[6]*g00 + coeffs[7]*b00 + (1 << (ITUR_BT_601_SHIFT - 1)) + (128 << ITUR_BT_601_SHIFT);
+            uchar* y = dst_->ptr<uchar>(2*i);
+            uchar* u = dst_->ptr<uchar>(h + i/2) + (i % 2) * (w/2);
+            uchar* v = dst_->ptr<uchar>(h + (i + h/2)/2) + ((i + h/2) % 2) * (w/2);
+            if( uIdx_ == 2 ) std::swap(u, v);
 
-            u[k] = saturate_cast<uchar>(u00 >> ITUR_BT_601_SHIFT);
-            v[k] = saturate_cast<uchar>(v00 >> ITUR_BT_601_SHIFT);
+            for( int j = 0, k = 0; j < w * cn; j += 2 * cn, k++ )
+            {
+                int r00 = row0[2-bIdx + j];      int g00 = row0[1 + j];      int b00 = row0[bIdx + j];
+                int r01 = row0[2-bIdx + cn + j]; int g01 = row0[1 + cn + j]; int b01 = row0[bIdx + cn + j];
+                int r10 = row1[2-bIdx + j];      int g10 = row1[1 + j];      int b10 = row1[bIdx + j];
+                int r11 = row1[2-bIdx + cn + j]; int g11 = row1[1 + cn + j]; int b11 = row1[bIdx + cn + j];
+
+                const int shifted16 = (16 << ITUR_BT_601_SHIFT);
+                const int halfShift = (1 << (ITUR_BT_601_SHIFT - 1));
+                int y00 = ITUR_BT_601_CRY * r00 + ITUR_BT_601_CGY * g00 + ITUR_BT_601_CBY * b00 + halfShift + shifted16;
+                int y01 = ITUR_BT_601_CRY * r01 + ITUR_BT_601_CGY * g01 + ITUR_BT_601_CBY * b01 + halfShift + shifted16;
+                int y10 = ITUR_BT_601_CRY * r10 + ITUR_BT_601_CGY * g10 + ITUR_BT_601_CBY * b10 + halfShift + shifted16;
+                int y11 = ITUR_BT_601_CRY * r11 + ITUR_BT_601_CGY * g11 + ITUR_BT_601_CBY * b11 + halfShift + shifted16;
+
+                y[2*k + 0]            = saturate_cast<uchar>(y00 >> ITUR_BT_601_SHIFT);
+                y[2*k + 1]            = saturate_cast<uchar>(y01 >> ITUR_BT_601_SHIFT);
+                y[2*k + dst_->step + 0] = saturate_cast<uchar>(y10 >> ITUR_BT_601_SHIFT);
+                y[2*k + dst_->step + 1] = saturate_cast<uchar>(y11 >> ITUR_BT_601_SHIFT);
+
+                const int shifted128 = (128 << ITUR_BT_601_SHIFT);
+                int u00 = ITUR_BT_601_CRU * r00 + ITUR_BT_601_CGU * g00 + ITUR_BT_601_CBU * b00 + halfShift + shifted128;
+                int v00 = ITUR_BT_601_CBU * r00 + ITUR_BT_601_CGV * g00 + ITUR_BT_601_CBV * b00 + halfShift + shifted128;
+
+                u[k] = saturate_cast<uchar>(u00 >> ITUR_BT_601_SHIFT);
+                v[k] = saturate_cast<uchar>(v00 >> ITUR_BT_601_SHIFT);
+            }
         }
     }
+
+    static bool isFit( const Mat& src )
+    {
+        return (src.total() >= 320*240);
+    }
+
+private:
+    RGB888toYUV420pInvoker& operator=(const RGB888toYUV420pInvoker&);
+
+    const Mat& src_;
+    Mat* const dst_;
+    const int uIdx_;
+};
+
+template<int bIdx, int uIdx>
+static void cvtRGBtoYUV420p(const Mat& src, Mat& dst)
+{
+    RGB888toYUV420pInvoker<bIdx> colorConverter(src, &dst, uIdx);
+    if( RGB888toYUV420pInvoker<bIdx>::isFit(src) )
+        parallel_for_(Range(0, src.rows/2), colorConverter);
+    else
+        colorConverter(Range(0, src.rows/2));
 }
 
 ///////////////////////////////////// YUV422 -> RGB /////////////////////////////////////