static Image2B resizeImage2B(int w, int h default widthToHeight(w, img), Image2B img) {
  if (img == null) null;
  int w1 = img.getWidth(), h1 = img.getHeight();
  if (w == w1 && h == h1) ret img;
  byte[] pixels1 = img.pixels, pixels2 = new byte[(w*h+7)/8];
  int i = 0;
  double y1 = 0, ystep = doubleRatio(h1, h), xstep = doubleRatio(w1, w);
  for y to h: {
    int i1 = ifloor(y1)*w1;
    y1 += ystep;
    double x1 = 0;
    for x to w: {
      int i2 = i1+ifloor(x1);
      if ((pixels1[i2/8] & (1 << (i2 & 7))) != 0)
        pixels2[i/8] |= 1 << (i & 7);
      x1 += xstep;
      i++;
    }
  }
  ret new Image2B(w, h, pixels2);
}