gistfile1.java

  public int getPixelBilinear(double x, double y)
    {
      // 座標値を画像の中に収める
      if (x < 0) x = 0.0;
      if (x >= this.getWidth()) x = this.getWidth() - 1.0;
      if (y < 0) y = 0.0;
      if (y >= this.getHeight()) y = this.getHeight() - 1.0;

      int x1 = (int)x;  // x - x1 == p
      int y1 = (int)y;  // y - y1 == q
      double p = x - (int)x;
      double q = y - (int)y;

      int fx1 = getPixel(x1, y1);
      int fx2 = getPixel(x1 + 1, y1);
      int fx = bilinearColorInterpolate(fx1, fx2, p);

      int fy1 = fx1;
      int fy2 = getPixel(x1, y1 + 1);
      int fx = bilinearColorInterpolate(fy1, fy2, q);

      return bilinearColorInterpolate(fx, fy, 0.5);
    }