source: GTP/trunk/App/Demos/Vis/FriendlyCulling/src/ToneMapper.cpp @ 2970

#include "ToneMapper.h"
#include "FrameBufferObject.h"


using namespace std;


namespace CHCDemoEngine 
{


ToneMapper::ToneMapper()
{
}


float ToneMapper::CalcImageKey(float *pixels, int w, int h) const
{
        float totalLum = .0f;

        int size = w * h * 4;

        // get avg log luminance
        for (int i = 0; i < size; i += 4)
        {
                float r = pixels[i + 0];
                float g = pixels[i + 1];
                float b = pixels[i + 2];

                float pixLum = 0.2125f * r + 0.7154f * g + 0.0721f * b;

                totalLum += log(pixLum + 1e-6f);
        }

        const float key = exp(totalLum / (float)(w * h));

        static float previousKey = key;
        const float factor = 0.5f;

        float imageKey;

        if (key > 0)
                imageKey = key * factor + previousKey * (1.0f - factor);
        else 
                imageKey = previousKey;

        previousKey = imageKey;
        
        //cout << "key: " << key << endl;

        return imageKey;
}


float ToneMapper::CalcMaxLuminance(float *pixels, int w, int h) const
{
        float maxLum = 1e-6f;

        int size = w * h * 4;

        for (int i = 0; i < size; i += 4)
        {
                float r = pixels[i + 0];
                float g = pixels[i + 1];
                float b = pixels[i + 2];

                float pixLum = 0.2125f * r + 0.7154f * g + 0.0721f * b;

                if (pixLum > maxLum)
                        maxLum = pixLum;
        }

/*      for (int i = 0; i < h; ++ i)
        {
                for (int j = 0; j < w; ++ j)
                {
                        const int idx = i * w + j;

                        float r = pixels[4 * idx + 0];
                        float g = pixels[4 * idx + 1];
                        float b = pixels[4 * idx + 2];

                        if (pixLum > maxLum)
                                maxLum = pixLum;
                }
        }
*/
        return maxLum;
}


}