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Lab and Luv tests: rewritten, constants explained

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pull/9374/head
Rostislav Vasilikhin 8 years ago
parent 0e6c335077
commit f0ef7bd149
1 changed files with 76 additions and 53 deletions
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  1. 129
      modules/imgproc/test/test_color.cpp

129
modules/imgproc/test/test_color.cpp
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@ -1010,10 +1010,6 @@ double CV_ColorLabTest::get_success_error_level( int /*test_case_idx*/, int i, i
} }
static const double _1_3 = 0.333333333333;
const static float _1_3f = static_cast<float>(_1_3);
void CV_ColorLabTest::convert_row_bgr2abc_32f_c3(const float* src_row, float* dst_row, int n) void CV_ColorLabTest::convert_row_bgr2abc_32f_c3(const float* src_row, float* dst_row, int n)
{ {
int depth = test_mat[INPUT][0].depth(); int depth = test_mat[INPUT][0].depth();
@ -1021,6 +1017,15 @@ void CV_ColorLabTest::convert_row_bgr2abc_32f_c3(const float* src_row, float* ds
float ab_bias = depth == CV_8U ? 128.f : depth == CV_16U ? 32768.f : 0.f; float ab_bias = depth == CV_8U ? 128.f : depth == CV_16U ? 32768.f : 0.f;
float M[9]; float M[9];
// 7.787f = (29/3)^3/(29*4)
static const float lowScale = 29.f*29.f/(27.f*4.f);
// 0.008856f = (6/29)^3
static const float lthresh = 6.f*6.f*6.f/(29.f*29.f*29.f);
// 903.3 = (29/3)^3
static const float yscale = 29.f*29.f*29.f/27.f;
static const float f16of116 = 16.f/116.f;
for (int j = 0; j < 9; j++ ) for (int j = 0; j < 9; j++ )
M[j] = (float)RGB2XYZ[j]; M[j] = (float)RGB2XYZ[j];
@ -1031,25 +1036,14 @@ void CV_ColorLabTest::convert_row_bgr2abc_32f_c3(const float* src_row, float* ds
float B = src_row[x]; float B = src_row[x];
float X = (R * M[0] + G * M[1] + B * M[2]) / Xn; float X = (R * M[0] + G * M[1] + B * M[2]) / Xn;
float Y = R * M[3] + G * M[4] + B * M[5]; float Y = R * M[3] + G * M[4] + B * M[5];
float Z = (R * M[6] + G * M[7] + B * M[8]) / Zn; float Z = (R * M[6] + G * M[7] + B * M[8]) / Zn;
float fX = X > 0.008856f ? pow(X, _1_3f) :
(7.787f * X + 16.f / 116.f);
float fZ = Z > 0.008856f ? pow(Z, _1_3f):
(7.787f * Z + 16.f / 116.f);
float L = 0.0f, fY = 0.0f; float fX = X > lthresh ? cubeRoot(X) : (lowScale * X + f16of116);
if (Y > 0.008856f) float fY = Y > lthresh ? cubeRoot(Y) : (lowScale * Y + f16of116);
{ float fZ = Z > lthresh ? cubeRoot(Z) : (lowScale * Z + f16of116);
fY = pow(Y, _1_3f);
L = 116.f * fY - 16.f;
}
else
{
fY = 7.787f * Y + 16.f / 116.f;
L = 903.3f * Y;
}
float L = Y > lthresh ? (116.f*fY - 16.f) : (yscale*Y);
float a = 500.f * (fX - fY); float a = 500.f * (fX - fY);
float b = 200.f * (fY - fZ); float b = 200.f * (fY - fZ);
@ -1069,8 +1063,16 @@ void CV_ColorLabTest::convert_row_abc2bgr_32f_c3( const float* src_row, float* d
for(int j = 0; j < 9; j++ ) for(int j = 0; j < 9; j++ )
M[j] = (float)XYZ2RGB[j]; M[j] = (float)XYZ2RGB[j];
static const float lthresh = 903.3f * 0.008856f; // 0.008856f * 903.3f = (6/29)^3*(29/3)^3 = 8
static const float thresh = 7.787f * 0.008856f + 16.0f / 116.0f; static const float lThresh = 8.f;
// 7.787f * 0.008856f + 16.0f / 116.0f = 6/29
static const float fThresh = 6.f/29.f;
static const float lbias = 16.f/116.f;
// 7.787f = (29/3)^3/(29*4)
static const float lowScale = 29.f*29.f/(27.f*4.f);
// 903.3 = (29/3)^3
static const float yscale = 29.f*29.f*29.f/27.f;
for (int x = 0, end = n * 3; x < end; x += 3) for (int x = 0, end = n * 3; x < end; x += 3)
{ {
float L = src_row[x] * Lscale; float L = src_row[x] * Lscale;
@ -1078,10 +1080,10 @@ void CV_ColorLabTest::convert_row_abc2bgr_32f_c3( const float* src_row, float* d
float b = src_row[x + 2] - ab_bias; float b = src_row[x + 2] - ab_bias;
float FY = 0.0f, Y = 0.0f; float FY = 0.0f, Y = 0.0f;
if (L <= lthresh) if (L <= lThresh)
{ {
Y = L / 903.3f; Y = L / yscale;
FY = 7.787f * Y + 16.0f / 116.0f; FY = lowScale * Y + lbias;
} }
else else
{ {
@ -1095,8 +1097,8 @@ void CV_ColorLabTest::convert_row_abc2bgr_32f_c3( const float* src_row, float* d
float FXZ[] = { FX, FZ }; float FXZ[] = { FX, FZ };
for (int k = 0; k < 2; ++k) for (int k = 0; k < 2; ++k)
{ {
if (FXZ[k] <= thresh) if (FXZ[k] <= fThresh)
FXZ[k] = (FXZ[k] - 16.0f / 116.0f) / 7.787f; FXZ[k] = (FXZ[k] - lbias) / lowScale;
else else
FXZ[k] = FXZ[k] * FXZ[k] * FXZ[k]; FXZ[k] = FXZ[k] * FXZ[k] * FXZ[k];
} }
@ -1155,25 +1157,37 @@ void CV_ColorLuvTest::convert_row_bgr2abc_32f_c3( const float* src_row, float* d
{ {
int depth = test_mat[INPUT][0].depth(); int depth = test_mat[INPUT][0].depth();
float Lscale = depth == CV_8U ? 255.f/100.f : depth == CV_16U ? 65535.f/100.f : 1.f; float Lscale = depth == CV_8U ? 255.f/100.f : depth == CV_16U ? 65535.f/100.f : 1.f;
static const float uLow = -134.f, uHigh = 220.f, uRange = uHigh - uLow;
static const float vLow = -140.f, vHigh = 122.f, vRange = vHigh - vLow;
int j; int j;
float M[9]; float M[9];
float un = 4.f*Xn/(Xn + 15.f*1.f + 3*Zn); // Yn == 1
float vn = 9.f*1.f/(Xn + 15.f*1.f + 3*Zn); float dd = Xn + 15.f*1.f + 3.f*Zn;
float un = 4.f*13.f*Xn/dd;
float vn = 9.f*13.f/dd;
float u_scale = 1.f, u_bias = 0.f; float u_scale = 1.f, u_bias = 0.f;
float v_scale = 1.f, v_bias = 0.f; float v_scale = 1.f, v_bias = 0.f;
for( j = 0; j < 9; j++ ) for( j = 0; j < 9; j++ )
M[j] = (float)RGB2XYZ[j]; M[j] = (float)RGB2XYZ[j];
//0.72033 = 255/(220+134), 96.525 = 134*255/(220+134)
//0.9732 = 255/(140+122), 136.259 = 140*255/(140+122)
if( depth == CV_8U ) if( depth == CV_8U )
{ {
u_scale = 0.720338983f; u_scale = 255.f/uRange;
u_bias = 96.5254237f; u_bias = -uLow*255.f/uRange;
v_scale = 0.973282442f; v_scale = 255.f/vRange;
v_bias = 136.2595419f; v_bias = -vLow*255.f/vRange;
} }
// 0.008856f = (6/29)^3
static const float lthresh = 6.f*6.f*6.f/(29.f*29.f*29.f);
// 903.3 = (29/3)^3
static const float yscale = 29.f*29.f*29.f/27.f;
for( j = 0; j < n*3; j += 3 ) for( j = 0; j < n*3; j += 3 )
{ {
float r = src_row[j+2]; float r = src_row[j+2];
@ -1189,14 +1203,14 @@ void CV_ColorLuvTest::convert_row_bgr2abc_32f_c3( const float* src_row, float* d
L = u = v = 0; L = u = v = 0;
else else
{ {
if( Y > 0.008856f ) if( Y > lthresh )
L = (float)(116.*pow((double)Y,_1_3) - 16.); L = 116.f*cubeRoot(Y) - 16.f;
else else
L = 903.3f * Y; L = yscale * Y;
d = 1.f/d; d = 4.f*13.f/d;
u = 13*L*(4*X*d - un); u = L*(X*d - un);
v = 13*L*(9*Y*d - vn); v = L*(9.f/4.f*Y*d - vn);
} }
dst_row[j] = L*Lscale; dst_row[j] = L*Lscale;
dst_row[j+1] = u*u_scale + u_bias; dst_row[j+1] = u*u_scale + u_bias;
@ -1209,24 +1223,34 @@ void CV_ColorLuvTest::convert_row_abc2bgr_32f_c3( const float* src_row, float* d
{ {
int depth = test_mat[INPUT][0].depth(); int depth = test_mat[INPUT][0].depth();
float Lscale = depth == CV_8U ? 100.f/255.f : depth == CV_16U ? 100.f/65535.f : 1.f; float Lscale = depth == CV_8U ? 100.f/255.f : depth == CV_16U ? 100.f/65535.f : 1.f;
static const float uLow = -134.f, uHigh = 220.f, uRange = uHigh - uLow;
static const float vLow = -140.f, vHigh = 122.f, vRange = vHigh - vLow;
int j; int j;
float M[9]; float M[9];
float un = 4.f*Xn/(Xn + 15.f*1.f + 3*Zn); // Yn == 1
float vn = 9.f*1.f/(Xn + 15.f*1.f + 3*Zn); float dd = Xn + 15.f*1.f + 3.f*Zn;
float un = 4*13.f*Xn/dd;
float vn = 9*13.f*1.f/dd;
float u_scale = 1.f, u_bias = 0.f; float u_scale = 1.f, u_bias = 0.f;
float v_scale = 1.f, v_bias = 0.f; float v_scale = 1.f, v_bias = 0.f;
for( j = 0; j < 9; j++ ) for( j = 0; j < 9; j++ )
M[j] = (float)XYZ2RGB[j]; M[j] = (float)XYZ2RGB[j];
//0.72033 = 255/(220+134), 96.525 = 134*255/(220+134)
//0.9732 = 255/(140+122), 136.259 = 140*255/(140+122)
if( depth == CV_8U ) if( depth == CV_8U )
{ {
u_scale = 1.f/0.720338983f; u_scale = uRange/255.f;
u_bias = 96.5254237f; u_bias = -uLow*255.f/uRange;
v_scale = 1.f/0.973282442f; v_scale = vRange/255.f;
v_bias = 136.2595419f; v_bias = -vLow*255.f/vRange;
} }
// (1 / 903.3) = (3/29)^3
static const float yscale = 27.f/(29.f*29.f*29.f);
for( j = 0; j < n*3; j += 3 ) for( j = 0; j < n*3; j += 3 )
{ {
float L = src_row[j]*Lscale; float L = src_row[j]*Lscale;
@ -1241,16 +1265,15 @@ void CV_ColorLuvTest::convert_row_abc2bgr_32f_c3( const float* src_row, float* d
} }
else else
{ {
Y = L * (1.f/903.3f); Y = L * yscale;
if( L == 0 )
L = 0.001f;
} }
u = u/(13*L) + un; float up = 3.f*(u + L*un);
v = v/(13*L) + vn; float vp = 0.25f/(v + L*vn);
if(vp > 0.25f) vp = 0.25f;
X = -9*Y*u/((u - 4)*v - u*v); if(vp < -0.25f) vp = -0.25f;
Z = (9*Y - 15*v*Y - v*X)/(3*v); X = Y*3.f*up*vp;
Z = Y*(((12.f*13.f)*L - up)*vp - 5.f);
float r = M[0]*X + M[1]*Y + M[2]*Z; float r = M[0]*X + M[1]*Y + M[2]*Z;
float g = M[3]*X + M[4]*Y + M[5]*Z; float g = M[3]*X + M[4]*Y + M[5]*Z;

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