wo ist der fehler?

dither.cpp

// dither()

    float p11 = image[w * y + x];
    float sw11 = 1.f;
    if(p11 < 0.5) sw11 = 0.f;
    float qe = p11 - sw11;
    float p12 = image[w * y + _clamp(0, w, (x + 1))];
    float p20 = image[_clamp(0, h, (w * (y + 1))) + _clamp(0, w, (x - 1))];
    float p21 = image[_clamp(0, h, (w * (y + 1))) + x];
    float p22 = image[_clamp(0, h, (w * (y + 1))) + _clamp(0, w, (x + 1))];
    image[w * y + _clamp(0, w, (x + 1))] = p12 + 7 * qe / 16.f;
    image[_clamp(0, h, (w * (y + 1))) + _clamp(0, w, (x - 1))] = p20 + 3 * qe / 16.f;
    image[_clamp(0, h, (w * (y + 1))) + x] = p21 + 2 * qe / 16.f;
    image[_clamp(0, h, (w * (y + 1))) + _clamp(0, w, (x + 1))] = p22 + 1 * qe / 16.f;
    image[w * y + x] = sw11;

// initialize()

// [...]

    float * imagef = new float[w * h];

    for(int y = 0; y < h; ++y)
    for(int x = 0; x < w; ++x) {
        QColor c11(image.pixel(x, y));
        imagef[y * w + x] =  c11.valueF();
    }

    for(int y = 0; y < h; ++y)
    for(int x = 0; x < w; ++x)
        dither(imagef, x, y, w, h);

    for(int y = 0; y < h; ++y)
    for(int x = 0; x < w; ++x)
    {
        image.setPixel(x, y, imagef[w * y + x]);
    }

    delete imagef;

    m_dithered = new QGraphicsPixmapItem(QPixmap::fromImage(image));

// [...]

zeile 36

zeile 13