static uint32_t adler32(Mat m)

{

uint32_t s1 = 1, s2 = 0;

for(int y = 0; y < m.rows; y++)

{

uchar* py = m.ptr(y);

for(size_t x = 0; x < m.cols*m.elemSize(); x++)

{

s1 = (s1 + py[x]) % 65521;

s2 = (s1 + s2 ) % 65521;

}

}

return (s2 << 16) + s1;

}

static ushort sRGBGammaTab_b[256], linearGammaTab_b[256];

enum { inv_gamma_shift = 12, INV_GAMMA_TAB_SIZE = (1 << inv_gamma_shift) };

static ushort sRGBInvGammaTab_b[INV_GAMMA_TAB_SIZE], linearInvGammaTab_b[INV_GAMMA_TAB_SIZE];

#undef lab_shift

#define lab_shift 12

#define gamma_shift 3

#define lab_shift2 (lab_shift + gamma_shift)

#define LAB_CBRT_TAB_SIZE_B (256*3/2*(1<<gamma_shift))

static ushort LabCbrtTab_b[LAB_CBRT_TAB_SIZE_B];

{

lab_base_shift = 14,

LAB_BASE = (1 << lab_base_shift),

};

#define CV_DESCALE(x,n) (((x) + (1 << ((n)-1))) >> (n))

static ushort LabToYF_b[256*2];

static const int minABvalue = -8145;

static int abToXZ_b[LAB_BASE*9/4];

static void initLabTabs()

{

static bool initialized = false;

if(!initialized)

{

static const softfloat lthresh = softfloat(216) / softfloat(24389); // 0.008856f = (6/29)^3

static const softfloat lscale = softfloat(841) / softfloat(108); // 7.787f = (29/3)^3/(29*4)

static const softfloat lbias = softfloat(16) / softfloat(116);

static const softfloat f255(255);

static const softfloat intScale(255*(1 << gamma_shift));

for(int i = 0; i < 256; i++)

{

softfloat x = softfloat(i)/f255;

sRGBGammaTab_b[i] = (ushort)(cvRound(intScale*applyGamma(x)));

linearGammaTab_b[i] = (ushort)(i*(1 << gamma_shift));

}

static const softfloat invScale = softfloat::one()/softfloat((int)INV_GAMMA_TAB_SIZE);

for(int i = 0; i < INV_GAMMA_TAB_SIZE; i++)

{

softfloat x = invScale*softfloat(i);

sRGBInvGammaTab_b[i] = (ushort)(cvRound(f255*applyInvGamma(x)));

linearInvGammaTab_b[i] = (ushort)(cvTrunc(f255*x));

}

static const softfloat cbTabScale(softfloat::one()/(f255*(1 << gamma_shift)));

static const softfloat lshift2(1 << lab_shift2);

for(int i = 0; i < LAB_CBRT_TAB_SIZE_B; i++)

{

softfloat x = cbTabScale*softfloat(i);

LabCbrtTab_b[i] = (ushort)(cvRound(lshift2 * (x < lthresh ? mulAdd(x, lscale, lbias) : cbrt(x))));

}

//Lookup table for L to y and ify calculations

static const int BASE = (1 << 14);

for(int i = 0; i < 256; i++)

{

int y, ify;

//8 * 255.0 / 100.0 == 20.4

if( i <= 20)

{

//yy = li / 903.3f;

//y = L*100/903.3f; 903.3f = (29/3)^3, 255 = 17*3*5

y = cvRound(softfloat(i*BASE*20*9)/softfloat(17*29*29*29));

//fy = 7.787f * yy + 16.0f / 116.0f; 7.787f = (29/3)^3/(29*4)

ify = cvRound(softfloat(BASE)*(softfloat(16)/softfloat(116) + softfloat(i*5)/softfloat(3*17*29)));

}

else

{

//fy = (li + 16.0f) / 116.0f;

softfloat fy = (softfloat(i*100*BASE)/softfloat(255*116) +

softfloat(16*BASE)/softfloat(116));

ify = cvRound(fy);

//yy = fy * fy * fy;

y = cvRound(fy*fy*fy/softfloat(BASE*BASE));

}

LabToYF_b[i*2 ] = (ushort)y; // 2260 <= y <= BASE

LabToYF_b[i*2+1] = (ushort)ify; // 0 <= ify <= BASE

}

//Lookup table for a,b to x,z conversion

for(int i = minABvalue; i < LAB_BASE*9/4+minABvalue; i++)

{

int v;

//6.f/29.f*BASE = 3389.730

if(i <= 3390)

{

//fxz[k] = (fxz[k] - 16.0f / 116.0f) / 7.787f;

// 7.787f = (29/3)^3/(29*4)

v = i*108/841 - BASE*16/116*108/841;

}

else

{

//fxz[k] = fxz[k] * fxz[k] * fxz[k];

v = i*i/BASE*i/BASE;

}

abToXZ_b[i-minABvalue] = v; // -1335 <= v <= 88231

}

initialized = true;

}

}

static int row8uRGB2Lab(const uchar* src_row, uchar *dst_row, int n, int cn, int blue_idx, bool srgb)

{

int coeffs[9];

softdouble whitept[3] = {Xn, softdouble::one(), Zn};

static const softdouble lshift(1 << lab_shift);

for(int i = 0; i < 3; i++)

{

coeffs[i*3 + (blue_idx^2)] = cvRound(lshift*RGB2XYZ[i*3 ]/whitept[i]);

coeffs[i*3 + 1 ] = cvRound(lshift*RGB2XYZ[i*3+1]/whitept[i]);

coeffs[i*3 + (blue_idx )] = cvRound(lshift*RGB2XYZ[i*3+2]/whitept[i]);

}

const int Lscale = (116*255+50)/100;

const int Lshift = -((16*255*(1 << lab_shift2) + 50)/100);

const ushort* tab = srgb ? sRGBGammaTab_b : linearGammaTab_b;

for (int x = 0; x < n; x++)

{

int R = src_row[x*cn + 0],

G = src_row[x*cn + 1],

B = src_row[x*cn + 2];

R = tab[R], G = tab[G], B = tab[B];

int fX = LabCbrtTab_b[CV_DESCALE(R*coeffs[0] + G*coeffs[1] + B*coeffs[2], lab_shift)];

int fY = LabCbrtTab_b[CV_DESCALE(R*coeffs[3] + G*coeffs[4] + B*coeffs[5], lab_shift)];

int fZ = LabCbrtTab_b[CV_DESCALE(R*coeffs[6] + G*coeffs[7] + B*coeffs[8], lab_shift)];

int L = CV_DESCALE( Lscale*fY + Lshift, lab_shift2 );

int a = CV_DESCALE( 500*(fX - fY) + 128*(1 << lab_shift2), lab_shift2 );

int b = CV_DESCALE( 200*(fY - fZ) + 128*(1 << lab_shift2), lab_shift2 );

dst_row[x*3 ] = saturate_cast<uchar>(L);

dst_row[x*3 + 1] = saturate_cast<uchar>(a);

dst_row[x*3 + 2] = saturate_cast<uchar>(b);

}

return n;

}

int row8uLab2RGB(const uchar* src_row, uchar *dst_row, int n, int cn, int blue_idx, bool srgb)

{

static const int base_shift = 14;

static const int BASE = (1 << base_shift);

static const int shift = lab_shift+(base_shift-inv_gamma_shift);

int coeffs[9];

softdouble whitept[3] = {Xn, softdouble::one(), Zn};

static const softdouble lshift(1 << lab_shift);

for(int i = 0; i < 3; i++)

{

coeffs[i+(blue_idx )*3] = cvRound(lshift*XYZ2RGB[i ]*whitept[i]);

coeffs[i+ 1*3] = cvRound(lshift*XYZ2RGB[i+3]*whitept[i]);

coeffs[i+(blue_idx^2)*3] = cvRound(lshift*XYZ2RGB[i+6]*whitept[i]);

}

ushort* tab = srgb ? sRGBInvGammaTab_b : linearInvGammaTab_b;

for(int x = 0; x < n; x++)

{

uchar LL = src_row[x*3 ];

uchar aa = src_row[x*3 + 1];

uchar bb = src_row[x*3 + 2];

int ro, go, bo, xx, yy, zz, ify;

yy = LabToYF_b[LL*2 ];

ify = LabToYF_b[LL*2+1];

int adiv, bdiv;

//adiv = aa*BASE/500 - 128*BASE/500, bdiv = bb*BASE/200 - 128*BASE/200;

//approximations with reasonable precision

adiv = ((5*aa*53687 + (1 << 7)) >> 13) - 128*BASE/500;

bdiv = (( bb*41943 + (1 << 4)) >> 9) - 128*BASE/200+1;

int ifxz[] = {ify + adiv, ify - bdiv};

for(int k = 0; k < 2; k++)

{

int& v = ifxz[k];

v = abToXZ_b[v-minABvalue];

}

xx = ifxz[0]; /* yy = yy */; zz = ifxz[1];

ro = CV_DESCALE(coeffs[0]*xx + coeffs[1]*yy + coeffs[2]*zz, shift);

go = CV_DESCALE(coeffs[3]*xx + coeffs[4]*yy + coeffs[5]*zz, shift);

bo = CV_DESCALE(coeffs[6]*xx + coeffs[7]*yy + coeffs[8]*zz, shift);

ro = max(0, min((int)INV_GAMMA_TAB_SIZE-1, ro));

go = max(0, min((int)INV_GAMMA_TAB_SIZE-1, go));

bo = max(0, min((int)INV_GAMMA_TAB_SIZE-1, bo));

ro = tab[ro];

go = tab[go];

bo = tab[bo];

dst_row[x*cn ] = saturate_cast<uchar>(bo);

dst_row[x*cn + 1] = saturate_cast<uchar>(go);

dst_row[x*cn + 2] = saturate_cast<uchar>(ro);

if(cn == 4) dst_row[x*cn + 3] = 255;

}

return n;

}

int row8uLabChoose(const uchar* src_row, uchar *dst_row, int n, bool forward, int blue_idx, bool srgb)

{

if(forward)

return row8uRGB2Lab(src_row, dst_row, n, 3, blue_idx, srgb);

else

return row8uLab2RGB(src_row, dst_row, n, 3, blue_idx, srgb);

}

TEST(Imgproc_ColorLab_Full, bitExactness)

{

int codes[] = { CV_BGR2Lab, CV_RGB2Lab, CV_LBGR2Lab, CV_LRGB2Lab,

CV_Lab2BGR, CV_Lab2RGB, CV_Lab2LBGR, CV_Lab2LRGB};

string names[] = { "CV_BGR2Lab", "CV_RGB2Lab", "CV_LBGR2Lab", "CV_LRGB2Lab",

"CV_Lab2BGR", "CV_Lab2RGB", "CV_Lab2LBGR", "CV_Lab2LRGB" };

// need to be recalculated each time we change Lab algorithms, RNG or test system

const int nIterations = 8;

uint32_t hashes[] = {

0xca7d94c4, 0x34aeb79a, 0x7272c2cf, 0x62c2efed, 0x047cab77, 0x5e8dfb85, 0x10fed613, 0x34d2f4aa,

0x048bea9a, 0xbbe20ef2, 0x3274e88f, 0x710e9272, 0x9fd6cd59, 0x69d67639, 0x04742095, 0x9ef2b60b,

0x75b78f5b, 0x3fda9801, 0x374cc472, 0x3239e8ad, 0x94749b2d, 0x9362ac0c, 0xa4d7dd36, 0xe25ef694,

0x51d1b01d, 0xb0f6e3f5, 0x2b72a228, 0xb7429fa0, 0x799ba6bd, 0x2141d3d2, 0xb4dde471, 0x813b6e0f,

0x9c029161, 0xb51eb5ec, 0x460c3a09, 0x27724f63, 0xb446c9a8, 0x3adf1b61, 0xe6b0d30f, 0xd1078779,

0xfaa7525b, 0x5b6ea158, 0xdf3511f7, 0xf01dc02d, 0x5c663841, 0xce611ed4, 0x758ad851, 0xa43c3a1c,

0xed30f68c, 0xcb6babd9, 0xf38262b5, 0x608cb3db, 0x13425e5a, 0x6dc5fdc7, 0x9519090a, 0x87aa73d0,

0x8e9bf980, 0x46b98728, 0x0064591c, 0x7e1efc9b, 0xf0ec2465, 0x89a75c8d, 0x0d162fa7, 0xffea7a2f,

};

RNG rng(0);

// blueIdx x srgb x direction

for(int c = 0; c < 8; c++)

{

int v = c;

int blueIdx = (v % 2 != 0) ? 2 : 0; v /=2;

bool srgb = (v % 2 == 0); v /= 2;

bool forward = (v % 2 == 0);

for(int iter = 0; iter < nIterations; iter++)

{

Mat probe(256, 256, CV_8UC3), result;

rng.fill(probe, RNG::UNIFORM, 0, 255, true);

cvtColor(probe, result, codes[c]);

uint32_t h = adler32(result);

if(h != hashes[c*nIterations + iter])

{

initLabTabs();

cvtest::TS* ts = cvtest::TS::ptr();

vector<uchar> goldBuf(probe.cols*4);

uchar* goldRow = &goldBuf[0];

bool next = true;

for(int y = 0; next && y < probe.rows; y++)

{

uchar* probeRow = probe.ptr(y);

uchar* resultRow = result.ptr(y);

row8uLabChoose(probeRow, goldRow, probe.cols, forward, blueIdx, srgb);

for(int x = 0; next && x < probe.cols; x++)

{

uchar* px = probeRow + x*3;

uchar* gx = goldRow + x*3;

uchar* rx = resultRow + x*3;

if(gx[0] != rx[0] || gx[1] != rx[1] || gx[2] != rx[2])

{

next = false;

ts->printf(cvtest::TS::SUMMARY, "Error in: (%d, %d)\n", x, y);

ts->printf(cvtest::TS::SUMMARY, "Conversion code: %s\n", names[c].c_str());

ts->printf(cvtest::TS::SUMMARY, "Reference value: %d %d %d\n", gx[0], gx[1], gx[2]);

ts->printf(cvtest::TS::SUMMARY, "Actual value: %d %d %d\n", rx[0], rx[1], rx[2]);

ts->printf(cvtest::TS::SUMMARY, "Src value: %d %d %d\n", px[0], px[1], px[2]);

ts->printf(cvtest::TS::SUMMARY, "Size: (%d, %d)\n", probe.rows, probe.cols);

ts->set_failed_test_info(cvtest::TS::FAIL_BAD_ACCURACY);

ts->set_gtest_status();

break;

}

}

}

if(next)

// this place should never be reached

throw std::runtime_error("Test system error: hash function mismatch when results are the same");

}

}

}

}