int cmsDetectBlackPoint(LPcmsCIEXYZ BlackPoint, cmsHPROFILE hProfile, int Intent, DWORD dwFlags)
{    

    // v4 + perceptual & saturation intents does have its own black point

    if ((cmsGetProfileICCversion(hProfile) >= 0x4000000) &&
        (Intent == INTENT_PERCEPTUAL || Intent == INTENT_SATURATION)) {

       return GetV4PerceptualBlack(BlackPoint, hProfile, dwFlags);
    }


#ifdef HONOR_BLACK_POINT_TAG

    // v2, v4 rel/abs colorimetric
    if (cmsIsTag(hProfile, icSigMediaBlackPointTag) && 
                    Intent == INTENT_RELATIVE_COLORIMETRIC) {

        cmsCIEXYZ BlackXYZ, UntrustedBlackPoint, TrustedBlackPoint, MediaWhite;
        cmsCIELab Lab;

             // If black point is specified, then use it, 
        
             cmsTakeMediaBlackPoint(&BlackXYZ, hProfile);
             cmsTakeMediaWhitePoint(&MediaWhite, hProfile);

             // Black point is absolute XYZ, so adapt to D50 to get PCS value

             cmsAdaptToIlluminant(&UntrustedBlackPoint, &MediaWhite, cmsD50_XYZ(), &BlackXYZ);

             // Force a=b=0 to get rid of any chroma

             cmsXYZ2Lab(NULL, &Lab, &UntrustedBlackPoint);
             Lab.a = Lab.b = 0;
             if (Lab.L > 50) Lab.L = 50; // Clip to L* <= 50

             cmsLab2XYZ(NULL, &TrustedBlackPoint, &Lab);

             // Return BP as D50 relative or absolute XYZ (depends on flags)

             if (!(dwFlags & LCMS_BPFLAGS_D50_ADAPTED))
                    cmsAdaptToIlluminant(BlackPoint, cmsD50_XYZ(), &MediaWhite, &TrustedBlackPoint);
             else
                    *BlackPoint = TrustedBlackPoint;
    }

#endif
    
    // If output profile, discount ink-limiting

    if (Intent == INTENT_RELATIVE_COLORIMETRIC && 
            (cmsGetDeviceClass(hProfile) == icSigOutputClass) &&
            (cmsGetColorSpace(hProfile) == icSigCmykData))
                return BlackPointUsingPerceptualBlack(BlackPoint, hProfile, dwFlags);

    // Nope, compute BP using current intent.

    return BlackPointAsDarkerColorant(hProfile, Intent, BlackPoint, dwFlags);

}

// Get a media white point fixing some issues found in certain old profiles
cmsBool  _cmsReadMediaWhitePoint(cmsCIEXYZ* Dest, cmsHPROFILE hProfile)
{
    cmsCIEXYZ* Tag;

    _cmsAssert(Dest != NULL);

    Tag = (cmsCIEXYZ*) cmsReadTag(hProfile, cmsSigMediaWhitePointTag);

    // If no wp, take D50
    if (Tag == NULL) {
        *Dest = *cmsD50_XYZ();
        return TRUE;
    }

    // V2 display profiles should give D50
    if (cmsGetEncodedICCversion(hProfile) < 0x4000000) {

        if (cmsGetDeviceClass(hProfile) == cmsSigDisplayClass) {
            *Dest = *cmsD50_XYZ();
            return TRUE;
        }
    }

    // All seems ok
    *Dest = *Tag;
    return TRUE;
}

// Approximate a blackbody illuminant based on CHAD information
static
cmsFloat64Number CHAD2Temp(const cmsMAT3* Chad)
{
    // Convert D50 across inverse CHAD to get the absolute white point
    cmsVEC3 d, s;
    cmsCIEXYZ Dest;
    cmsCIExyY DestChromaticity;
    cmsFloat64Number TempK;
    cmsMAT3 m1, m2;

    m1 = *Chad;
    if (!_cmsMAT3inverse(&m1, &m2)) return FALSE;

    s.n[VX] = cmsD50_XYZ() -> X;
    s.n[VY] = cmsD50_XYZ() -> Y;
    s.n[VZ] = cmsD50_XYZ() -> Z;

    _cmsMAT3eval(&d, &m2, &s);

    Dest.X = d.n[VX];
    Dest.Y = d.n[VY];
    Dest.Z = d.n[VZ];

    cmsXYZ2xyY(&DestChromaticity, &Dest);

    if (!cmsTempFromWhitePoint(&TempK, &DestChromaticity))
        return -1.0;

    return TempK;
}

// Black point compensation. Implemented as a linear scaling in XYZ. Black points
// should come relative to the white point. Fills an matrix/offset element m
// which is organized as a 4x4 matrix.
static
void ComputeBlackPointCompensation(const cmsCIEXYZ* BlackPointIn,
                                   const cmsCIEXYZ* BlackPointOut,
                                   cmsMAT3* m, cmsVEC3* off)
{
  cmsFloat64Number ax, ay, az, bx, by, bz, tx, ty, tz;

   // Now we need to compute a matrix plus an offset m and of such of
   // [m]*bpin + off = bpout
   // [m]*D50  + off = D50
   //
   // This is a linear scaling in the form ax+b, where
   // a = (bpout - D50) / (bpin - D50)
   // b = - D50* (bpout - bpin) / (bpin - D50)

   tx = BlackPointIn->X - cmsD50_XYZ()->X;
   ty = BlackPointIn->Y - cmsD50_XYZ()->Y;
   tz = BlackPointIn->Z - cmsD50_XYZ()->Z;

   ax = (BlackPointOut->X - cmsD50_XYZ()->X) / tx;
   ay = (BlackPointOut->Y - cmsD50_XYZ()->Y) / ty;
   az = (BlackPointOut->Z - cmsD50_XYZ()->Z) / tz;

   bx = - cmsD50_XYZ()-> X * (BlackPointOut->X - BlackPointIn->X) / tx;
   by = - cmsD50_XYZ()-> Y * (BlackPointOut->Y - BlackPointIn->Y) / ty;
   bz = - cmsD50_XYZ()-> Z * (BlackPointOut->Z - BlackPointIn->Z) / tz;

   _cmsVEC3init(&m ->v[0], ax, 0,  0);
   _cmsVEC3init(&m ->v[1], 0, ay,  0);
   _cmsVEC3init(&m ->v[2], 0,  0,  az);
   _cmsVEC3init(off, bx, by, bz);

}

static
void EmitWhiteBlackD50(cmsIOHANDLER* m, cmsCIEXYZ* BlackPoint)
{

    _cmsIOPrintf(m, "/BlackPoint [%f %f %f]\n", BlackPoint -> X,
                                          BlackPoint -> Y,
                                          BlackPoint -> Z);

    _cmsIOPrintf(m, "/WhitePoint [%f %f %f]\n", cmsD50_XYZ()->X, 
                                          cmsD50_XYZ()->Y,
                                          cmsD50_XYZ()->Z);
}

// Chromatic adaptation matrix. Fix some issues as well
cmsBool  _cmsReadCHAD(cmsMAT3* Dest, cmsHPROFILE hProfile)
{
    cmsMAT3* Tag;

    _cmsAssert(Dest != NULL);

    Tag = (cmsMAT3*) cmsReadTag(hProfile, cmsSigChromaticAdaptationTag);

    if (Tag != NULL) {
        *Dest = *Tag;
        return TRUE;
    }

    // No CHAD available, default it to identity
    _cmsMAT3identity(Dest);

    // V2 display profiles should give D50
    if (cmsGetEncodedICCversion(hProfile) < 0x4000000) {

        if (cmsGetDeviceClass(hProfile) == cmsSigDisplayClass) {

            cmsCIEXYZ* White = (cmsCIEXYZ*) cmsReadTag(hProfile, cmsSigMediaWhitePointTag);

            if (White == NULL) {

                _cmsMAT3identity(Dest);
                return TRUE;
            }

            return _cmsAdaptationMatrix(Dest, NULL, White, cmsD50_XYZ());
        }
    }

    return TRUE;
}

LCMSAPI LPcmsCIExyY LCMSEXPORT cmsD50_xyY(void)
{
    static cmsCIExyY D50xyY;
    cmsXYZ2xyY(&D50xyY, cmsD50_XYZ());

    return &D50xyY;
}

const cmsCIExyY* CMSEXPORT cmsD50_xyY(void)
{
    static cmsCIExyY D50xyY;

    cmsXYZ2xyY(&D50xyY, cmsD50_XYZ());

    return &D50xyY;
}

// Compute a CHAD based on a given temperature
static
    void Temp2CHAD(cmsMAT3* Chad, cmsFloat64Number Temp)
{
    cmsCIEXYZ White;
    cmsCIExyY ChromaticityOfWhite;

    cmsWhitePointFromTemp(&ChromaticityOfWhite, Temp);
    cmsxyY2XYZ(&White, &ChromaticityOfWhite);
    _cmsAdaptationMatrix(Chad, NULL, &White, cmsD50_XYZ());
}

static
int BlackPointUsingPerceptualBlack(LPcmsCIEXYZ BlackPoint, 
                                   cmsHPROFILE hProfile, 
                                   DWORD dwFlags)
{
    cmsHTRANSFORM hPercLab2CMYK, hRelColCMYK2Lab;
    cmsHPROFILE hLab;
    cmsCIELab LabIn, LabOut;
    WORD CMYK[MAXCHANNELS];
    cmsCIEXYZ  BlackXYZ, MediaWhite;        


     if (!cmsIsIntentSupported(hProfile, INTENT_PERCEPTUAL, LCMS_USED_AS_INPUT)) {

        BlackPoint -> X = BlackPoint ->Y = BlackPoint -> Z = 0.0;
        return 0;
    }
   
    hLab = cmsCreateLabProfile(NULL);

    hPercLab2CMYK  = cmsCreateTransform(hLab, TYPE_Lab_DBL, 
                                        hProfile, TYPE_CMYK_16, 
                                        INTENT_PERCEPTUAL, cmsFLAGS_NOTPRECALC);

    hRelColCMYK2Lab = cmsCreateTransform(hProfile, TYPE_CMYK_16, 
                                         hLab, TYPE_Lab_DBL, 
                                         INTENT_RELATIVE_COLORIMETRIC, cmsFLAGS_NOTPRECALC);

    LabIn.L = LabIn.a = LabIn.b = 0;

    cmsDoTransform(hPercLab2CMYK, &LabIn, CMYK, 1);
    cmsDoTransform(hRelColCMYK2Lab, CMYK, &LabOut, 1);

    if (LabOut.L > 50) LabOut.L = 50;
    LabOut.a = LabOut.b = 0;

    cmsDeleteTransform(hPercLab2CMYK);
    cmsDeleteTransform(hRelColCMYK2Lab);
    cmsCloseProfile(hLab);

    cmsLab2XYZ(NULL, &BlackXYZ, &LabOut);   
    
    if (!(dwFlags & LCMS_BPFLAGS_D50_ADAPTED)){
            cmsTakeMediaWhitePoint(&MediaWhite, hProfile);
            cmsAdaptToIlluminant(BlackPoint, cmsD50_XYZ(), &MediaWhite, &BlackXYZ);
    }
    else
            *BlackPoint = BlackXYZ;
   
    return 1;

}

// Creates a fake NULL profile. This profile return 1 channel as always 0.
// Is useful only for gamut checking tricks
cmsHPROFILE CMSEXPORT cmsCreateNULLProfileTHR(cmsContext ContextID)
{
    cmsHPROFILE hProfile;
    cmsPipeline* LUT = NULL;
    cmsStage* PostLin;
    cmsToneCurve* EmptyTab;
    cmsUInt16Number Zero[2] = { 0, 0 };

    hProfile = cmsCreateProfilePlaceholder(ContextID);
    if (!hProfile)                          // can't allocate
        return NULL;

    cmsSetProfileVersion(hProfile, 4.3);

    if (!SetTextTags(hProfile, L"NULL profile built-in")) goto Error;



    cmsSetDeviceClass(hProfile, cmsSigOutputClass);
    cmsSetColorSpace(hProfile,  cmsSigGrayData);
    cmsSetPCS(hProfile,         cmsSigLabData);

    // An empty LUTs is all we need
    LUT = cmsPipelineAlloc(ContextID, 1, 1);
    if (LUT == NULL) goto Error;

    EmptyTab = cmsBuildTabulatedToneCurve16(ContextID, 2, Zero);
    PostLin = cmsStageAllocToneCurves(ContextID, 1, &EmptyTab);
    cmsFreeToneCurve(EmptyTab);

    if (!cmsPipelineInsertStage(LUT, cmsAT_END, PostLin))
        goto Error;

    if (!cmsWriteTag(hProfile, cmsSigBToA0Tag, (void*) LUT)) goto Error;
    if (!cmsWriteTag(hProfile, cmsSigMediaWhitePointTag, cmsD50_XYZ())) goto Error;

    cmsPipelineFree(LUT);
    return hProfile;

Error:

    if (LUT != NULL)
        cmsPipelineFree(LUT);

    if (hProfile != NULL)
        cmsCloseProfile(hProfile);

    return NULL;
}

BOOL cmsAdaptMatrixFromD50(LPMAT3 r, LPcmsCIExyY DestWhitePt)
{
        cmsCIEXYZ Dn;       
        MAT3 Bradford;
        MAT3 Tmp;

        cmsxyY2XYZ(&Dn, DestWhitePt);
        
        cmsAdaptationMatrix(&Bradford, NULL, cmsD50_XYZ(), &Dn);

        Tmp = *r;
        MAT3per(r, &Bradford, &Tmp);

        return TRUE;
}

BOOL cmsAdaptMatrixToD50(LPMAT3 r, LPcmsCIExyY SourceWhitePt)
{
        cmsCIEXYZ Dn;      
        MAT3 Bradford;
        MAT3 Tmp;

        cmsxyY2XYZ(&Dn, SourceWhitePt);
        
        cmsAdaptationMatrix(&Bradford, NULL, &Dn, cmsD50_XYZ());

        Tmp = *r;
        MAT3per(r, &Bradford, &Tmp);

        return TRUE;
}

/// WAS: Same as anterior, but assuming D50 source. White point is given in xyY
static cmsBool cmsAdaptMatrixFromD50(cmsMAT3* const r, const cmsCIExyY* const DestWhitePt)
{
    cmsCIEXYZ Dn;
    cmsMAT3 Bradford;
    cmsMAT3 Tmp;

    cmsxyY2XYZ(&Dn, DestWhitePt);

    if (!_cmsAdaptationMatrix(&Bradford, NULL, &Dn, cmsD50_XYZ()))
        return FALSE;

    Tmp = *r;
    _cmsMAT3per(r, &Bradford, &Tmp);

    return TRUE;
}

cmsHPROFILE _cmsCreateProfilePlaceholder(void)
{

    LPLCMSICCPROFILE Icc = (LPLCMSICCPROFILE) _cmsMalloc(sizeof(LCMSICCPROFILE));
    if (Icc == NULL) return NULL;

    // Empty values
    ZeroMemory(Icc, sizeof(LCMSICCPROFILE));

    // Make sure illuminant is correct
    Icc ->Illuminant = *cmsD50_XYZ();

    // Set it to empty
    Icc -> TagCount   = 0;

    // Return the handle
    return (cmsHPROFILE) Icc;
}

cmsHPROFILE LCMSEXPORT cmsCreateLinearizationDeviceLink(icColorSpaceSignature ColorSpace,
                                                        LPGAMMATABLE TransferFunctions[])
{
       cmsHPROFILE hICC;
       LPLUT Lut;
           
        
       hICC = _cmsCreateProfilePlaceholder();
       if (!hICC)                          // can't allocate
            return NULL;


       cmsSetDeviceClass(hICC,      icSigLinkClass);
       cmsSetColorSpace(hICC,       ColorSpace);
       cmsSetPCS(hICC,              ColorSpace);
       cmsSetRenderingIntent(hICC,  INTENT_PERCEPTUAL); 

     
       // Creates a LUT with prelinearization step only
       Lut = cmsAllocLUT();
       if (Lut == NULL) return NULL;

       // Set up channels
       Lut ->InputChan = Lut ->OutputChan = _cmsChannelsOf(ColorSpace);

       // Copy tables to LUT
       cmsAllocLinearTable(Lut, TransferFunctions, 1);

       // Create tags       
       cmsAddTag(hICC, icSigDeviceMfgDescTag,       (LPVOID) "(lcms internal)");
       cmsAddTag(hICC, icSigProfileDescriptionTag,  (LPVOID) "lcms linearization device link");
       cmsAddTag(hICC, icSigDeviceModelDescTag,     (LPVOID) "linearization built-in");      
    
       cmsAddTag(hICC, icSigMediaWhitePointTag, (LPVOID) cmsD50_XYZ());
       cmsAddTag(hICC, icSigAToB0Tag, (LPVOID) Lut);
       
       // LUT is already on virtual profile
       cmsFreeLUT(Lut);

       // Ok, done
       return hICC;
}

static LCMSBOOL updateHeader(LPLCMSICCPROFILE Icc) {
  icHeader head;

  readMemBuffer(&head, sizeof(icHeader), 1, Icc -> stream);

  // Stop processing if data are corrupted
  if (swapBytes32(head.magic) != icMagicNumber) return FALSE;

  Icc->Version = swapBytes32(head.version);
  Icc->DeviceClass = swapBytes32(head.deviceClass);
  Icc->ColorSpace = swapBytes32(head.colorSpace);
  Icc->PCS = swapBytes32(head.pcs);
  Icc->flags = swapBytes32(head.flags);
  Icc->RenderingIntent = (icRenderingIntent) swapBytes32(head.renderingIntent);

  // For now ICC spec states that illuminant should be D50 in all profiles
  Icc->Illuminant = *cmsD50_XYZ();

  return TRUE;
}

void updateCriticalTags(LPLCMSICCPROFILE Icc) {

  LPVOID savedData = NULL;

  int idx;

  cmsCIEXYZ* dummy;



  MemBuffer *memBuffer = (MemBuffer*) Icc->stream;



  if(!memBuffer->needsUpdateCriticalTags) // Nothing to do

    return;



  idx = findTag(Icc, icSigMediaWhitePointTag);

  dummy = cmsD50_XYZ();

  if(idx >= 0) { // There is media white point already     
    cmsAddTag(Icc, icSigMediaWhitePointTag, dummy); // Force LCMS to read critical tags
    free(Icc->TagPtrs[idx]); // Get rid of dummy media white point
    Icc->TagPtrs[idx] = NULL; 
  } else {
    cmsAddTag(Icc, icSigMediaWhitePointTag, dummy); // Force LCMS to read critical tags
    // Get rid of dummy media white point
    free(Icc->TagPtrs[Icc->TagCount-1]);
    Icc->TagPtrs[Icc->TagCount-1] = NULL;
    Icc->TagNames[Icc->TagCount-1] = 0;
    Icc->TagSizes[Icc->TagCount-1] = 0;
    Icc->TagOffsets[Icc->TagCount-1] = 0;
    Icc->TagCount--;
  }

  memBuffer->needsUpdateCriticalTags = FALSE;
}

// Get Perceptual black of v4 profiles.
static
int GetV4PerceptualBlack(LPcmsCIEXYZ BlackPoint, cmsHPROFILE hProfile, DWORD dwFlags)
{
        if (dwFlags & LCMS_BPFLAGS_D50_ADAPTED) {

            BlackPoint->X = PERCEPTUAL_BLACK_X;
            BlackPoint->Y = PERCEPTUAL_BLACK_Y;
            BlackPoint->Z = PERCEPTUAL_BLACK_Z;
        }
        else {

            cmsCIEXYZ D50BlackPoint, MediaWhite;

            cmsTakeMediaWhitePoint(&MediaWhite, hProfile);
            D50BlackPoint.X = PERCEPTUAL_BLACK_X; 
            D50BlackPoint.Y = PERCEPTUAL_BLACK_Y;
            D50BlackPoint.Z = PERCEPTUAL_BLACK_Z;
            cmsAdaptToIlluminant(BlackPoint, cmsD50_XYZ(), &MediaWhite, &D50BlackPoint);
        }


        return 1;
}

void LCMSEXPORT cmsLab2XYZ(LPcmsCIEXYZ WhitePoint, LPcmsCIEXYZ xyz,  const cmsCIELab* Lab)
{
        double x, y, z;

        if (Lab -> L <= 0) {
               xyz -> X = 0;
               xyz -> Y = 0;
               xyz -> Z = 0;
               return;
        }


       if (WhitePoint == NULL)
            WhitePoint = cmsD50_XYZ();

       y = (Lab-> L + 16.0) / 116.0;
       x = y + 0.002 * Lab -> a;
       z = y - 0.005 * Lab -> b;

       xyz -> X = f_1(x) * WhitePoint -> X;
       xyz -> Y = f_1(y) * WhitePoint -> Y;
       xyz -> Z = f_1(z) * WhitePoint -> Z;

}