chromium/third_party/pdfium/third_party/lcms/src/cmsgmt.c

//---------------------------------------------------------------------------------
//
//  Little Color Management System
//  Copyright (c) 1998-2021 Marti Maria Saguer
//
// Permission is hereby granted, free of charge, to any person obtaining
// a copy of this software and associated documentation files (the "Software"),
// to deal in the Software without restriction, including without limitation
// the rights to use, copy, modify, merge, publish, distribute, sublicense,
// and/or sell copies of the Software, and to permit persons to whom the Software
// is furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO
// THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
// NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
// LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
// OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
// WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
//
//---------------------------------------------------------------------------------
//

#include "lcms2_internal.h"


// Auxiliary: append a Lab identity after the given sequence of profiles
// and return the transform. Lab profile is closed, rest of profiles are kept open.
cmsHTRANSFORM _cmsChain2Lab(cmsContext            ContextID,
                            cmsUInt32Number        nProfiles,
                            cmsUInt32Number        InputFormat,
                            cmsUInt32Number        OutputFormat,
                            const cmsUInt32Number  Intents[],
                            const cmsHPROFILE      hProfiles[],
                            const cmsBool          BPC[],
                            const cmsFloat64Number AdaptationStates[],
                            cmsUInt32Number        dwFlags)
{ … }


// Compute K -> L* relationship. Flags may include black point compensation. In this case,
// the relationship is assumed from the profile with BPC to a black point zero.
static
cmsToneCurve* ComputeKToLstar(cmsContext            ContextID,
                               cmsUInt32Number       nPoints,
                               cmsUInt32Number       nProfiles,
                               const cmsUInt32Number Intents[],
                               const cmsHPROFILE     hProfiles[],
                               const cmsBool         BPC[],
                               const cmsFloat64Number AdaptationStates[],
                               cmsUInt32Number dwFlags)
{ … }


// Compute Black tone curve on a CMYK -> CMYK transform. This is done by
// using the proof direction on both profiles to find K->L* relationship
// then joining both curves. dwFlags may include black point compensation.
cmsToneCurve* _cmsBuildKToneCurve(cmsContext        ContextID,
                                   cmsUInt32Number   nPoints,
                                   cmsUInt32Number   nProfiles,
                                   const cmsUInt32Number Intents[],
                                   const cmsHPROFILE hProfiles[],
                                   const cmsBool     BPC[],
                                   const cmsFloat64Number AdaptationStates[],
                                   cmsUInt32Number   dwFlags)
{ … }


// Gamut LUT Creation -----------------------------------------------------------------------------------------

// Used by gamut & softproofing

GAMUTCHAIN;

// This sampler does compute gamut boundaries by comparing original
// values with a transform going back and forth. Values above ERR_THRESHOLD
// of maximum are considered out of gamut.

#define ERR_THRESHOLD …


static
int GamutSampler(CMSREGISTER const cmsUInt16Number In[], CMSREGISTER cmsUInt16Number Out[], CMSREGISTER void* Cargo)
{ … }

// Does compute a gamut LUT going back and forth across pcs -> relativ. colorimetric intent -> pcs
// the dE obtained is then annotated on the LUT. Values truly out of gamut are clipped to dE = 0xFFFE
// and values changed are supposed to be handled by any gamut remapping, so, are out of gamut as well.
//
// **WARNING: This algorithm does assume that gamut remapping algorithms does NOT move in-gamut colors,
// of course, many perceptual and saturation intents does not work in such way, but relativ. ones should.

cmsPipeline* _cmsCreateGamutCheckPipeline(cmsContext ContextID,
                                          cmsHPROFILE hProfiles[],
                                          cmsBool  BPC[],
                                          cmsUInt32Number Intents[],
                                          cmsFloat64Number AdaptationStates[],
                                          cmsUInt32Number nGamutPCSposition,
                                          cmsHPROFILE hGamut)
{ … }

// Total Area Coverage estimation ----------------------------------------------------------------

cmsTACestimator;


// This callback just accounts the maximum ink dropped in the given node. It does not populate any
// memory, as the destination table is NULL. Its only purpose it to know the global maximum.
static
int EstimateTAC(CMSREGISTER const cmsUInt16Number In[], CMSREGISTER cmsUInt16Number Out[], CMSREGISTER void * Cargo)
{ … }


// Detect Total area coverage of the profile
cmsFloat64Number CMSEXPORT cmsDetectTAC(cmsHPROFILE hProfile)
{ … }


// Carefully,  clamp on CIELab space.

cmsBool CMSEXPORT cmsDesaturateLab(cmsCIELab* Lab,
                                   double amax, double amin,
                                   double bmax, double bmin)
{ … }

// Detect whatever a given ICC profile works in linear (gamma 1.0) space
// Actually, doing that "well" is quite hard, since every component may behave completely different.
// Since the true point of this function is to detect suitable optimizations, I am imposing some requirements 
// that simplifies things: only RGB, and only profiles that can got in both directions.
// The algorithm obtains Y from a syntetical gray R=G=B. Then least squares fitting is used to estimate gamma. 
// For gamma close to 1.0, RGB is linear. On profiles not supported, -1 is returned.

cmsFloat64Number CMSEXPORT cmsDetectRGBProfileGamma(cmsHPROFILE hProfile, cmsFloat64Number threshold)
{ … }