//---------------------------------------------------------------------------------

//  Little Color Management System

//  Copyright (c) 1998-2010 Marti Maria Saguer

//

//---------------------------------------------------------------------------------

//

#include "lcms2_internal.h"

// This file contains routines for resampling and LUT optimization, black point detection

// and black preservation.

// Black point detection -------------------------------------------------------------------------

// PCS -> PCS round trip transform, always uses relative intent on the device -> pcs

static

cmsHTRANSFORM CreateRoundtripXForm(cmsHPROFILE hProfile, cmsUInt32Number nIntent)

    cmsHPROFILE hLab = cmsCreateLab4Profile(NULL);

    cmsHTRANSFORM xform;

    cmsBool BPC[4] = { FALSE, FALSE, FALSE, FALSE };

    cmsFloat64Number States[4] = { 1.0, 1.0, 1.0, 1.0 };

    cmsHPROFILE hProfiles[4];

    cmsUInt32Number Intents[4];

    cmsContext ContextID = cmsGetProfileContextID(hProfile);

    hProfiles[0] = hLab; hProfiles[1] = hProfile; hProfiles[2] = hProfile; hProfiles[3] = hLab;

    Intents[0]   = INTENT_RELATIVE_COLORIMETRIC; Intents[1] = nIntent; Intents[2] = INTENT_RELATIVE_COLORIMETRIC; Intents[3] = INTENT_RELATIVE_COLORIMETRIC;

    xform =  cmsCreateExtendedTransform(ContextID, 4, hProfiles, BPC, Intents,

        States, NULL, 0, TYPE_Lab_DBL, TYPE_Lab_DBL, cmsFLAGS_NOCACHE|cmsFLAGS_NOOPTIMIZE);

    cmsCloseProfile(hLab);

    return xform;

}

// Use darker colorants to obtain black point. This works in the relative colorimetric intent and

// assumes more ink results in darker colors. No ink limit is assumed.

static

cmsBool  BlackPointAsDarkerColorant(cmsHPROFILE    hInput,

                                    cmsUInt32Number Intent,

                                    cmsCIEXYZ* BlackPoint,

                                    cmsUInt32Number dwFlags)

{

    cmsUInt16Number *Black;

    cmsHTRANSFORM xform;

    cmsColorSpaceSignature Space;

    cmsUInt32Number nChannels;

    cmsUInt32Number dwFormat;

    cmsHPROFILE hLab;

    cmsCIELab  Lab;

    cmsCIEXYZ  BlackXYZ;

    cmsContext ContextID = cmsGetProfileContextID(hInput);

    // 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 FALSE;

    }

    // Create a formatter which has n channels and floating point

    dwFormat = cmsFormatterForColorspaceOfProfile(hInput, 2, FALSE);

   // Try to get black by using black colorant

    Space = cmsGetColorSpace(hInput);

    // This function returns darker colorant in 16 bits for several spaces

    if (!_cmsEndPointsBySpace(Space, NULL, &Black, &nChannels)) {

        BlackPoint -> X = BlackPoint ->Y = BlackPoint -> Z = 0.0;

        return FALSE;

    }

    if (nChannels != T_CHANNELS(dwFormat)) {

       BlackPoint -> X = BlackPoint ->Y = BlackPoint -> Z = 0.0;

       return FALSE;

    }

    // Lab will be used as the output space, but lab2 will avoid recursion

    hLab = cmsCreateLab2ProfileTHR(ContextID, NULL);

    if (hLab == NULL) {

       BlackPoint -> X = BlackPoint ->Y = BlackPoint -> Z = 0.0;

       return FALSE;

    }

    // Create the transform

    xform = cmsCreateTransformTHR(ContextID, hInput, dwFormat,

                                hLab, TYPE_Lab_DBL, Intent, cmsFLAGS_NOOPTIMIZE|cmsFLAGS_NOCACHE);

    cmsCloseProfile(hLab);

    if (xform == NULL) {

        // Something went wrong. Get rid of open resources and return zero as black

        BlackPoint -> X = BlackPoint ->Y = BlackPoint -> Z = 0.0;

        return FALSE;

    }

    // Convert black to Lab

    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;

    // Free the resources

    cmsDeleteTransform(xform);

    // Convert from Lab (which is now clipped) to XYZ.

    cmsLab2XYZ(NULL, &BlackXYZ, &Lab);

    if (BlackPoint != NULL)

        *BlackPoint = BlackXYZ;

    return TRUE;

    cmsUNUSED_PARAMETER(dwFlags);

}

// Get a black point of output CMYK profile, discounting any ink-limiting embedded

// in the profile. For doing that, we use perceptual intent in input direction:

// Lab (0, 0, 0) -> [Perceptual] Profile -> CMYK -> [Rel. colorimetric] Profile -> Lab

static

cmsBool BlackPointUsingPerceptualBlack(cmsCIEXYZ* BlackPoint, cmsHPROFILE hProfile)

{

    cmsHTRANSFORM hRoundTrip;

    cmsCIELab LabIn, LabOut;

    cmsCIEXYZ  BlackXYZ;

     // Is the intent supported by the profile?

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

        BlackPoint -> X = BlackPoint ->Y = BlackPoint -> Z = 0.0;

        return TRUE;

    }

    hRoundTrip = CreateRoundtripXForm(hProfile, INTENT_PERCEPTUAL);

    if (hRoundTrip == NULL) {

        BlackPoint -> X = BlackPoint ->Y = BlackPoint -> Z = 0.0;

        return FALSE;

    }

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

    cmsDoTransform(hRoundTrip, &LabIn, &LabOut, 1);

    // Clip Lab to reasonable limits

    if (LabOut.L > 50) LabOut.L = 50;

    LabOut.a = LabOut.b = 0;

    cmsDeleteTransform(hRoundTrip);

    // Convert it to XYZ

    cmsLab2XYZ(NULL, &BlackXYZ, &LabOut);

    if (BlackPoint != NULL)

        *BlackPoint = BlackXYZ;

// 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. There is a special flag for using black point tag, but turned

// off by default because it is bogus on most profiles. The detection algorithm

// involves to turn BP to neutral and to use only L component.

cmsBool CMSEXPORT cmsDetectBlackPoint(cmsCIEXYZ* BlackPoint, cmsHPROFILE hProfile, cmsUInt32Number Intent, cmsUInt32Number dwFlags)

    // Zero for black point

    if (cmsGetDeviceClass(hProfile) == cmsSigLinkClass) {

        BlackPoint -> X = BlackPoint ->Y = BlackPoint -> Z = 0.0;

        return FALSE;

    // v4 + perceptual & saturation intents does have its own black point, and it is

    // well specified enough to use it. Black point tag is deprecated in V4.

    if ((cmsGetEncodedICCversion(hProfile) >= 0x4000000) &&

        (Intent == INTENT_PERCEPTUAL || Intent == INTENT_SATURATION)) {

            // Matrix shaper share MRC & perceptual intents

            if (cmsIsMatrixShaper(hProfile))

                return BlackPointAsDarkerColorant(hProfile, INTENT_RELATIVE_COLORIMETRIC, BlackPoint, 0);

            // Get Perceptual black out of v4 profiles. That is fixed for perceptual & saturation intents

            BlackPoint -> X = cmsPERCEPTUAL_BLACK_X;

            BlackPoint -> Y = cmsPERCEPTUAL_BLACK_Y;

            BlackPoint -> Z = cmsPERCEPTUAL_BLACK_Z;

            return TRUE;

#ifdef CMS_USE_PROFILE_BLACK_POINT_TAG

    // v2, v4 rel/abs colorimetric

    if (cmsIsTag(hProfile, cmsSigMediaBlackPointTag) &&

        Intent == INTENT_RELATIVE_COLORIMETRIC) {

            cmsCIEXYZ *BlackPtr, BlackXYZ, UntrustedBlackPoint, TrustedBlackPoint, MediaWhite;

            cmsCIELab Lab;

            // If black point is specified, then use it,

            BlackPtr = cmsReadTag(hProfile, cmsSigMediaBlackPointTag);

            if (BlackPtr != NULL) {

                BlackXYZ = *BlackPtr;

                _cmsReadMediaWhitePoint(&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);

                if (BlackPoint != NULL)

                    *BlackPoint = TrustedBlackPoint;

                return TRUE;

            }

    // That is about v2 profiles.

    // If output profile, discount ink-limiting and that's all

    if (Intent == INTENT_RELATIVE_COLORIMETRIC &&

        (cmsGetDeviceClass(hProfile) == cmsSigOutputClass) &&

        (cmsGetColorSpace(hProfile)  == cmsSigCmykData))

        return BlackPointUsingPerceptualBlack(BlackPoint, hProfile);

    // Nope, compute BP using current intent.

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