wo is der fehler?

dither_2.cpp

/* dither() */
    float p11 = image[w * y + x];
    float sw11 = 1.f;
    if(p11 < 0.5) sw11 = 0.f;
    float qe = p11 - sw11;
    image[              w *  y        +               x      ]  = sw11;
    image[              w *  y        + _clamp(0, w, (x + 1))] += 7.f * qe / 16.f;
    image[_clamp(0, h, (w * (y + 1))) + _clamp(0, w, (x - 1))] += 3.f * qe / 16.f; //@TODO: Not applied, why?
    image[_clamp(0, h, (w * (y + 1))) +               x      ] += 5.f * qe / 16.f; //@TODO: Not applied, why?
    image[_clamp(0, h, (w * (y + 1))) + _clamp(0, w, (x + 1))] += 1.f * qe / 16.f; //@TODO: Not applied, why?


/* initialize() */
    // Creates a 1d float array with gray values of an image
    float * imagef = new float[w * h];
    for(int y = 0; y < h; ++y)
    for(int x = 0; x < w; ++x) {
        QColor c11(m_image->pixel(x, y));
        imagef[w * y + x] =  c11.valueF();
    }
    // Applies Floyd-Steinberg dither
    for(int y = 0; y < h; ++y)
    for(int x = 0; x < w; ++x)
        dither(imagef, x, y, w, h);
    // Draws dithered image from float array
    for(int y = 0; y < h; ++y)
    for(int x = 0; x < w; ++x) {
        QColor c11;
        float value = _clamp(0.f, 1.f, imagef[w * y + x]);
        c11.setRgbF(value, value, value);
        image.setPixel(x, y, c11.rgb());
    }