cmswtpnt.c

Linux下的无线网卡通用驱动程序

    double uj,vj,tj,di,dj,mi,mj;
    double Tc = -1, xs, ys;

    di = mi = 0;
    xs = v -> x;
    ys = v -> y;

    // convert (x,y) to CIE 1960 (u,v) 

    us = (2*xs) / (-xs + 6*ys + 1.5);
    vs = (3*ys) / (-xs + 6*ys + 1.5);


    for (j=0; j < NISO; j++) {

        uj = isotempdata[j].ut;
        vj = isotempdata[j].vt;
        tj = isotempdata[j].tt;
        mj = isotempdata[j].mirek;

        dj = ((vs - vj) - tj * (us - uj)) / sqrt(1 + tj*tj);



        if ((j!=0) && (di/dj < 0.0)) {
            Tc = 1000000.0 / (mi + (di / (di - dj)) * (mj - mi));
            break;
        }

        di = dj;
        mi = mj;
    }


    if (j == NISO) return -1;   
    return Tc;
}



static
BOOL InRange(LPcmsCIExyY a, LPcmsCIExyY b, double tolerance)
{
       double dist_x, dist_y;

       dist_x = fabs(a->x - b->x);
       dist_y = fabs(a->y - b->y);

       return (tolerance >= dist_x * dist_x + dist_y * dist_y);

}


typedef struct {
                char Name[30];
                cmsCIExyY Val;

              } WHITEPOINTS,FAR *LPWHITEPOINTS;

static
int FromD40toD150(LPWHITEPOINTS pts)
{
       int i, n;

       n = 0;
       for (i=40; i < 150; i ++)
       {
              sprintf(pts[n].Name, "D%d", i);
              cmsWhitePointFromTemp((int) (i*100.0), &pts[n].Val);
              n++;
       }

   return n;
}


void _cmsIdentifyWhitePoint(char *Buffer, LPcmsCIEXYZ WhitePt)
{
       int i, n;
       cmsCIExyY Val;
       double T;
       WHITEPOINTS SomeIlluminants[140] = {

                                   {"CIE illuminant A", {0.4476, 0.4074, 1.0}},
                                   {"CIE illuminant C", {0.3101, 0.3162, 1.0}},
                                   {"D65 (daylight)",   {0.3127, 0.3291, 1.0}},
                                   };

              n = FromD40toD150(&SomeIlluminants[3]) + 3;

              cmsXYZ2xyY(&Val, WhitePt);

              Val.Y = 1.;
              for (i=0; i < n; i++)
              {

                            if (InRange(&Val, &SomeIlluminants[i].Val, 0.000005))
                            {
                                strcpy(Buffer, "WhitePoint : ");
                                strcat(Buffer, SomeIlluminants[i].Name);                                
                                return;
                            }
              }

              T = Robertson(&Val);

              if (T > 0) 
                sprintf(Buffer, "White point near %dK", (int) T);                                                     
              else
              {
              sprintf(Buffer, "Unknown white point (X:%1.2g, Y:%1.2g, Z:%1.2g)",
                                          WhitePt -> X, WhitePt -> Y, WhitePt -> Z);
              
              }
              
}


// Use darker colorant to obtain black point

static
int BlackPointAsDarkerColorant(cmsHPROFILE hInput,                               
                               int Intent,
                               LPcmsCIEXYZ BlackPoint,
                               DWORD dwFlags)
{
    WORD *Black, *White;
    cmsHTRANSFORM xform;
    icColorSpaceSignature Space;
    int nChannels;
    DWORD dwFormat; 
    cmsHPROFILE hLab;
    cmsCIELab  Lab;
    cmsCIEXYZ  BlackXYZ, MediaWhite;        
    
    // If the profile does not support input direction, assume Black point 0
    
    if (!cmsIsIntentSupported(hInput, Intent, LCMS_USED_AS_INPUT)) {

        BlackPoint -> X = BlackPoint ->Y = BlackPoint -> Z = 0.0;
        return 0;
    }
    

    // Try to get black by using black colorant

    Space = cmsGetColorSpace(hInput);
    
    if (!_cmsEndPointsBySpace(Space, &White, &Black, &nChannels)) {
        
        BlackPoint -> X = BlackPoint ->Y = BlackPoint -> Z = 0.0;
        return 0;
    }
    
    dwFormat = CHANNELS_SH(nChannels)|BYTES_SH(2);

    hLab = cmsCreateLabProfile(NULL);
    
    xform = cmsCreateTransform(hInput, dwFormat,
                                hLab, TYPE_Lab_DBL, Intent, cmsFLAGS_NOTPRECALC);
    
    
    cmsDoTransform(xform, Black, &Lab, 1);

    // Force it to be neutral, clip to max. L* of 50

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

    cmsCloseProfile(hLab);
    cmsDeleteTransform(xform);
    
    cmsLab2XYZ(NULL, &BlackXYZ, &Lab);
    
    if (Intent == INTENT_ABSOLUTE_COLORIMETRIC) {
        
        *BlackPoint = BlackXYZ; 
    }
    else {
        
        if (!(dwFlags & LCMS_BPFLAGS_D50_ADAPTED)) {

            cmsTakeMediaWhitePoint(&MediaWhite, hInput);
            cmsAdaptToIlluminant(BlackPoint, cmsD50_XYZ(), &MediaWhite, &BlackXYZ);
        }
        else
            *BlackPoint = BlackXYZ;
    }
        
    return 1;
}


// Get a black point of output CMYK profile, discounting any ink-limiting embedded 
// in the profile. Fou doing that, use perceptual intent in input direction:
// Lab (0, 0, 0) -> [Perceptual] Profile -> CMYK -> [Rel. colorimetric] Profile -> Lab

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;

}


// 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;
}


// This function shouldn't exist at all -- there is such quantity of broken
// profiles on black point tag, that we must somehow fix chromaticity to 
// avoid huge tint when doing Black point compensation. This function does
// just that. If BP is specified, then forces it to neutral and uses only L
// component. If does not exist, computes it by taking 400% of ink or RGB=0 This
// works well on relative intent and is undefined on perceptual & saturation.
// However, I will support all intents for tricking & trapping.


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)) {

       // Matrix shaper share MRC & perceptual intents

       if (_cmsIsMatrixShaper(hProfile)) 
           return BlackPointAsDarkerColorant(hProfile, INTENT_RELATIVE_COLORIMETRIC, BlackPoint, cmsFLAGS_NOTPRECALC);

       // Get fixed value
       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;

             return 1;
    }

#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);

}