static IIntegralImage scaledIntegralImage(IIntegralImage img, int w) {

  ret scaledIntegralImage(img, w, iround(w*img.getHeight()/(double) img.getWidth()));

}

static IIntegralImage scaledIntegralImage(IIntegralImage img, int w, int h) {

  ret new IIntegralImage {

    int w1 = img.getWidth(), h1 = img.getHeight();

    double factorX = doubleRatio(w1, w);

    double factorY = doubleRatio(h1, h);

    double areaCorrection = 1/(factorX*factorY);

    public int getWidth() { ret w; }

    public int getHeight() { ret h; }

    // get value for 1 channel

    // normal range [0; pixelCount*256)

    // TODO: test

    public double getIntegralValue(int x, int y, int channel) {

      double x2 = (x+1)*factorX-1;

      double y2 = (y+1)*factorY-1;

      double val = img.getIntegralValue(x2, y2, channel);

      ifdef scaledIntegralImage_debug

        printVars scaledIntegralImage(+x, +y, +x2, +y2, +val, val2 := val*areaCorrection);

      endifdef

      ret val*areaCorrection;

    }

  };

}