sclass BWII_MultiPatternFinder implements Iterable<FoundImg> {

  new L<BWImage> patternImages;

  L<Int> scaleWidths = ll(25, 35, 50, 75, 100); // widths to scale input image to

  transient BWIntegralImage ii;

  transient IBWImage scaled;

  transient BWImage pattern;

  transient FoundImg found;

  transient int currentScaleWidth;

  *() {}

  *(L<BWImage> *patternImages, BWIntegralImage *ii) {}

  // only call once

  public Iterator<FoundImg> iterator() {

    ret nonNullIterator(nestedIterator(scaleWidths, func(int scaleWidth) -> Iterator<FoundImg> {

      currentScaleWidth = scaleWidth;

      ret mapI(patternImages, func(BWImage pat) {

        pattern = pat;

        FoundImg lastFound = found;

        if (scaled == null || scaled.getWidth() != scaleWidth)

          scaled = virtualScaledIntegralImageBW(ii, scaleWidth);

        FoundImg found2 = bwImageSearch_best_virtualBig(scaled, pat, found == null ? 0f : found.sim);

        if (found2 != null)

          ret found = found2;

        null;

      });

    }));

  }

}