rawTherapee/rtengine/expo_before_b.cc

////////////////////////////////////////////////////////////////
//
//      //exposure correction before interpolation
//
//  code dated: December 27, 2010
//
//  Expo_before.cc is free software: you can redistribute it and/or modify
//  it under the terms of the GNU General Public License as published by
//  the Free Software Foundation, either version 3 of the License, or
//  (at your option) any later version.
//
//  This program is distributed in the hope that it will be useful,
//  but WITHOUT ANY WARRANTY; without even the implied warranty of
//  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
//  GNU General Public License for more details.
//
//  You should have received a copy of the GNU General Public License
//  along with this program.  If not, see <http://www.gnu.org/licenses/>.
//
////////////////////////////////////////////////////////////////



//           Jacques Desmis <jdesmis@gmail.com>
//           use fast-demo(provisional) from Emil Martinec
//           inspired from work Guillermo Luijk and Manuel LLorens(Perfectraw)
//           Ingo Weyrich (2014-07-07)
//              optimized the highlight protection case
//              needs 2*width*height*sizeof(float) byte less memory than before
//              needs about 60% less processing time than before
//
// This function uses parameters:
//      exposure (linear): 2^(-8..0..8): currently 0.5 +3
//      preserve (log)   : 0..8 : currently 0.1 1

#include "rtengine.h"
#include "rawimagesource.h"
#include "mytime.h"
#include "rt_math.h"

namespace rtengine
{

extern const Settings* settings;

void RawImageSource::processRawWhitepoint(float expos, float preser)
{
    MyTime t1e, t2e;

    if (settings->verbose) {
        t1e.set();
    }

    int width = W, height = H;
    // exposure correction inspired from G.Luijk

    for (int c = 0; c < 4; c++) {
        chmax[c] *= expos;
    }

    if (fabs(preser) < 0.001f) {
        // No highlight protection - simple mutiplication

        if (ri->getSensorType() == ST_BAYER || ri->getSensorType() == ST_FUJI_XTRANS)
            #pragma omp parallel for
            for (int row = 0; row < height; row++)
                for (int col = 0; col < width; col++) {
                    rawData[row][col] *= expos;
                }
        else
            #pragma omp parallel for
            for (int row = 0; row < height; row++)
                for (int col = 0; col < width; col++) {
                    rawData[row][col * 3] *= expos;
                    rawData[row][col * 3 + 1] *= expos;
                    rawData[row][col * 3 + 2] *= expos;
                }
    } else {
        if (ri->getSensorType() == ST_BAYER || ri->getSensorType() == ST_FUJI_XTRANS) {
            // Demosaic to allow calculation of luminosity.
            if(ri->getSensorType() == ST_BAYER) {
                fast_demosaic (0, 0, W, H);
            } else {
                fast_xtrans_interpolate();
            }
        }

        // Find maximum to adjust LUTs. New float engines clips only at the very end
        float maxValFloat = 0.f;
        #pragma omp parallel
        {
            float maxValFloatThr = 0.f;

            if (ri->getSensorType() == ST_BAYER || ri->getSensorType() == ST_FUJI_XTRANS)
                #pragma omp for schedule(dynamic,16) nowait
                for(int row = 0; row < height; row++)
                    for (int col = 0; col < width; col++) {
                        if (rawData[row][col] > maxValFloatThr) {
                            maxValFloatThr = rawData[row][col];
                        }
                    }
            else
                #pragma omp for schedule(dynamic,16) nowait
                for(int row = 0; row < height; row++)
                    for (int col = 0; col < width; col++) {
                        for (int c = 0; c < 3; c++)
                            if (rawData[row][col * 3 + c] > maxValFloatThr) {
                                maxValFloatThr = rawData[row][col * 3 + c];
                            }
                    }

            #pragma omp critical
            {
                if(maxValFloatThr > maxValFloat) {
                    maxValFloat = maxValFloatThr;
                }
            }
        }

        // Exposure correction with highlight preservation
        int maxVal = maxValFloat;
        LUTf lut(maxVal + 1);
        float K;

        if(expos > 1) {
            // Positive exposure
            K = (float) maxVal / expos * exp(-preser * log(2.0));

            for (int j = max(1, (int)K); j <= maxVal; j++) {
                lut[(int)j] = (((float)maxVal - K * expos) / ((float)maxVal - K) * (j - maxVal) + (float) maxVal) / j;
            }
        } else {
            // Negative exposure
            float EV = log(expos) / log(2.0);                          // Convert exp. linear to EV
            K = (float)maxVal * exp(-preser * log(2.0));

            for (int j = 0; j <= maxVal; j++) {
                lut[(int)j] = exp(EV * ((float)maxVal - j) / ((float)maxVal - K) * log(2.0));
            }
        }

        if (ri->getSensorType() == ST_BAYER || ri->getSensorType() == ST_FUJI_XTRANS)
            #pragma omp parallel for schedule(dynamic,16)
            for(int row = 0; row < height; row++)
                for(int col = 0; col < width; col++) {
                    float lumi = 0.299f * red[row][col] + 0.587f * green[row][col] + 0.114f * blue[row][col];
                    rawData[row][col] *= lumi < K ? expos : lut[lumi];
                }
        else
            #pragma omp parallel for
            for(int row = 0; row < height; row++)
                for(int col = 0; col < width; col++) {
                    float lumi = 0.299f * rawData[row][col * 3] + 0.587f * rawData[row][col * 3 + 1] + 0.114f * rawData[row][col * 3 + 2];
                    float fac = lumi < K ? expos : lut[lumi];

                    for (int c = 0; c < 3; c++) {
                        rawData[row][col * 3 + c] *= fac;
                    }
                }

    }

    if (settings->verbose) {
        t2e.set();
        printf("Exposure before %d usec\n", t2e.etime(t1e));
    }

}

} //namespace