sclass FaceFinderX1 extends F1<RGBImage, Rect> {
  int y1, y2, deltaX1, deltaX2;
  
  public Rect get(RGBImage img) {
    //print(f2s(img.file));
    RGBImage img2 = rgbClipLineRange(img, y1, y2);
    float[] f = rgbImageColumnBrightnesses(img2);
    //printStruct(f);
    int x = indexOfSmallestFloat(f);
    ret rectFromPoints(x+deltaX1, y1, x+deltaX2, y2);
  }
  
  toString { ret sfu(this); }
}