public static float BoxIntegral(IntegralImage img, int row, int col, int rows, int cols) {
int height = img.getHeight();
int width = img.getWidth();
// The subtraction by one for row/col is because row/col is inclusive.
int r1 = Math.min(row, height) - 1;
int c1 = Math.min(col, width) - 1;
int r2 = Math.min(row + rows, height) - 1;
int c2 = Math.min(col + cols, width) - 1;
float A = (r1 >= 0 && c1 >= 0) ? img.getValue(c1, r1) : 0;
float B = (r1 >= 0 && c2 >= 0) ? img.getValue(c2, r1) : 0;
float C = (r2 >= 0 && c1 >= 0) ? img.getValue(c1, r2) : 0;
float D = (r2 >= 0 && c2 >= 0) ? img.getValue(c2, r2) : 0;
// System.out.println("height = " + height + ", width = " + width);
// System.out.println("c1 = " + c1 + ", c2 = " + c2 + ", r1 = " + r1 + ", r2 = " + r2);
// System.out.println("A = " + A + ", B = " + B + ", C = " + C + ", D = " + D);
return Math.max(0F, A - B - C + D);
}
