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Commit 4d2b74ae authored by Dichen Zhang's avatar Dichen Zhang
Browse files

ultrahdr icc: update transfer function 

Bug: 286444758
Test: jpegr_test.cpp
Manual test:
(1) append icc package to red-noicc.jpeg (attached in
the bug comment #1), then open the image with digital color meter, color measurement should be close to (255, 0, 0).
(2) Dump icc into a file and open the icc file on Mac, read data of each component (wtpt, r/g/bXYZ, r/g/bTRC) that should be the same as the samples in comment #10

Change-Id: I3b4a2b7d283fc143207d2dbce570eadf7568ebec
parent 301980e5

libs/ultrahdr/icc.cpp

+30 −15
Original line number Diff line number Diff line
@@ -19,7 +19,6 @@ 
#endif



#include <ultrahdr/icc.h>

#include <ultrahdr/gainmapmath.h>

#include <vector>

#include <utils/Log.h>
@@ -227,14 +226,30 @@ sp<DataStruct> IccHelper::write_trc_tag(const int table_entries, const void* tab 
    return dataStruct;

}



sp<DataStruct> IccHelper::write_trc_tag_for_linear() {

sp<DataStruct> IccHelper::write_trc_tag(const TransferFunction& fn) {

    if (fn.a == 1.f && fn.b == 0.f && fn.c == 0.f

            && fn.d == 0.f && fn.e == 0.f && fn.f == 0.f) {

        int total_length = 16;

    sp<DataStruct> dataStruct = sp<DataStruct>::make(total_length);

        sp<DataStruct> dataStruct = new DataStruct(total_length);

        dataStruct->write32(Endian_SwapBE32(kTAG_ParaCurveType));  // Type

        dataStruct->write32(0);                                    // Reserved

        dataStruct->write32(Endian_SwapBE16(kExponential_ParaCurveType));

    dataStruct->write32(Endian_SwapBE32(float_round_to_fixed(1.0)));

        dataStruct->write32(Endian_SwapBE32(float_round_to_fixed(fn.g)));

        return dataStruct;

    }



    int total_length = 40;

    sp<DataStruct> dataStruct = new DataStruct(total_length);

    dataStruct->write32(Endian_SwapBE32(kTAG_ParaCurveType));  // Type

    dataStruct->write32(0);                                    // Reserved

    dataStruct->write32(Endian_SwapBE16(kGABCDEF_ParaCurveType));

    dataStruct->write32(Endian_SwapBE32(float_round_to_fixed(fn.g)));

    dataStruct->write32(Endian_SwapBE32(float_round_to_fixed(fn.a)));

    dataStruct->write32(Endian_SwapBE32(float_round_to_fixed(fn.b)));

    dataStruct->write32(Endian_SwapBE32(float_round_to_fixed(fn.c)));

    dataStruct->write32(Endian_SwapBE32(float_round_to_fixed(fn.d)));

    dataStruct->write32(Endian_SwapBE32(float_round_to_fixed(fn.e)));

    dataStruct->write32(Endian_SwapBE32(float_round_to_fixed(fn.f)));

    return dataStruct;

}
@@ -349,7 +364,7 @@ sp<DataStruct> IccHelper::write_mAB_or_mBA_tag(uint32_t type, 


    // The "B" curve is required.

    for (size_t i = 0; i < kNumChannels; ++i) {

        b_curves_data[i] = write_trc_tag_for_linear();

        b_curves_data[i] = write_trc_tag(kLinear_TransFun);

    }



    // The "A" curve and CLUT are optional.
@@ -362,7 +377,7 @@ sp<DataStruct> IccHelper::write_mAB_or_mBA_tag(uint32_t type, 


        a_curves_offset = clut_offset + clut->getLength();

        for (size_t i = 0; i < kNumChannels; ++i) {

            a_curves_data[i] = write_trc_tag_for_linear();

            a_curves_data[i] = write_trc_tag(kLinear_TransFun);

        }

    }
@@ -460,9 +475,9 @@ sp<DataStruct> IccHelper::writeIccProfile(ultrahdr_transfer_function tf, 
            tags.emplace_back(kTAG_bTRC,

                    write_trc_tag(kTrcTableSize, reinterpret_cast<uint8_t*>(trc_table.data())));

        } else {

            tags.emplace_back(kTAG_rTRC, write_trc_tag_for_linear());

            tags.emplace_back(kTAG_gTRC, write_trc_tag_for_linear());

            tags.emplace_back(kTAG_bTRC, write_trc_tag_for_linear());

            tags.emplace_back(kTAG_rTRC, write_trc_tag(kSRGB_TransFun));

            tags.emplace_back(kTAG_gTRC, write_trc_tag(kSRGB_TransFun));

            tags.emplace_back(kTAG_bTRC, write_trc_tag(kSRGB_TransFun));

        }

    }

libs/ultrahdr/include/ultrahdr/gainmapmath.h

+17 −0
Original line number Diff line number Diff line
@@ -51,6 +51,23 @@ struct Color { 
typedef Color (*ColorTransformFn)(Color);

typedef float (*ColorCalculationFn)(Color);



// A transfer function mapping encoded values to linear values,

// represented by this 7-parameter piecewise function:

//

//   linear = sign(encoded) *  (c*|encoded| + f)       , 0 <= |encoded| < d

//          = sign(encoded) * ((a*|encoded| + b)^g + e), d <= |encoded|

//

// (A simple gamma transfer function sets g to gamma and a to 1.)

typedef struct TransferFunction {

    float g, a,b,c,d,e,f;

} TransferFunction;



static constexpr TransferFunction kSRGB_TransFun =

    { 2.4f, (float)(1/1.055), (float)(0.055/1.055), (float)(1/12.92), 0.04045f, 0.0f, 0.0f };



static constexpr TransferFunction kLinear_TransFun =

    { 1.0f, 1.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f };



inline Color operator+=(Color& lhs, const Color& rhs) {

  lhs.r += rhs.r;

  lhs.g += rhs.g;

libs/ultrahdr/include/ultrahdr/icc.h

+2 −1
Original line number Diff line number Diff line
@@ -17,6 +17,7 @@ 
#ifndef ANDROID_ULTRAHDR_ICC_H

#define ANDROID_ULTRAHDR_ICC_H



#include <ultrahdr/gainmapmath.h>

#include <ultrahdr/jpegr.h>

#include <ultrahdr/jpegrutils.h>

#include <utils/RefBase.h>
@@ -222,7 +223,7 @@ private: 
                                       const ultrahdr_color_gamut gamut);

    static sp<DataStruct> write_xyz_tag(float x, float y, float z);

    static sp<DataStruct> write_trc_tag(const int table_entries, const void* table_16);

    static sp<DataStruct> write_trc_tag_for_linear();

    static sp<DataStruct> write_trc_tag(const TransferFunction& fn);

    static float compute_tone_map_gain(const ultrahdr_transfer_function tf, float L);

    static sp<DataStruct> write_cicp_tag(uint32_t color_primaries,

                                         uint32_t transfer_characteristics);