rewrote color conversion functions; added sRGB<->CIE Lab/Luv conversion; added RGB<->YUV conversion; improved [s]RGB->Lab conversion speed

modules/core/include/opencv2/core/operations.hpp

@@ -3266,6 +3266,41 @@ partition( const vector<_Tp>& _vec, vector<int>& labels,
     return nclasses;
 }
 
+// computes cubic spline coefficients for a function: (xi=i, yi=f[i]), i=0..n
+template<typename _Tp> static void splineBuild(const _Tp* f, int n, _Tp* tab)
+{
+    _Tp cn = 0;
+    int i;
+    tab[0] = tab[1] = (_Tp)0;
+    
+    for(i = 1; i < n-1; i++)
+    {
+        _Tp t = 3*(f[i+1] - 2*f[i] + f[i-1]);
+        _Tp l = 1/(4 - tab[(i-1)*4]);
+        tab[i*4] = l; tab[i*4+1] = (t - tab[(i-1)*4+1])*l;
+    }
+    
+    for(i = n-1; i >= 0; i--)
+    {
+        _Tp c = tab[i*4+1] - tab[i*4]*cn;
+        _Tp b = f[i+1] - f[i] - (cn + c*2)*(_Tp)0.3333333333333333;
+        _Tp d = (cn - c)*(_Tp)0.3333333333333333;
+        tab[i*4] = f[i]; tab[i*4+1] = b;
+        tab[i*4+2] = c; tab[i*4+3] = d;
+        cn = c;
+    }
+}
+    
+// interpolates value of a function at x, 0 <= x <= n using a cubic spline.
+template<typename _Tp> static inline _Tp splineInterpolate(_Tp x, const _Tp* tab, int n)
+{
+    int ix = cvFloor(x);
+    ix = std::min(std::max(ix, 0), n-1);
+    x -= ix;
+    tab += ix*4;
+    return ((tab[3]*x + tab[2])*x + tab[1])*x + tab[0];
+}
+
 //////////////////////////////////////////////////////////////////////////////
 
 // bridge C++ => C Seq API

modules/imgproc/include/opencv2/imgproc/types_c.h

@@ -206,6 +206,21 @@ enum
     CV_HLS2BGR_FULL = 72,
     CV_HLS2RGB_FULL = 73,
     
+    CV_LBGR2Lab     = 74,
+    CV_LRGB2Lab     = 75,
+    CV_LBGR2Luv     = 76,
+    CV_LRGB2Luv     = 77,
+    
+    CV_Lab2LBGR     = 78,
+    CV_Lab2LRGB     = 79,
+    CV_Luv2LBGR     = 80,
+    CV_Luv2LRGB     = 81,
+    
+    CV_BGR2YUV      = 82,
+    CV_RGB2YUV      = 83,
+    CV_YUV2BGR      = 84,
+    CV_YUV2RGB      = 85,
+    
 	CV_COLORCVT_MAX  =100
 };