Flagging.cpp

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#include "SEFramework/Aperture/Flagging.h"
 
namespace SourceXtractor {
 
const SeFloat CROWD_THRESHOLD_APER = 0.1;
const SeFloat BADAREA_THRESHOLD_APER = 0.1;
 
Flags computeFlags(const std::shared_ptr<Aperture>& aperture,
                   SeFloat centroid_x, SeFloat centroid_y,
                   const std::vector<PixelCoordinate>& pix_list,
                   const std::shared_ptr<Image<SeFloat>>& detection_img,
                   const std::shared_ptr<Image<SeFloat>>& detection_variance,
                   const std::shared_ptr<Image<SeFloat>>& threshold_image,
                   SeFloat variance_threshold) {
 
  Flags flag = Flags::NONE;
  // get the aperture borders on the image
  auto min_pixel = aperture->getMinPixel(centroid_x, centroid_y);
  auto max_pixel = aperture->getMaxPixel(centroid_x, centroid_y);
 
  // clip to the actual image
  if (min_pixel.clip(detection_img->getWidth(), detection_img->getHeight()))
    flag |= Flags::BOUNDARY;
  if (max_pixel.clip(detection_img->getWidth(), detection_img->getHeight()))
    flag |= Flags::BOUNDARY;
 
  // cut the bit of image we need
  auto var_cutout = detection_variance->getChunk(min_pixel, max_pixel);
 
  // get the neighbourhood information
  NeighbourInfo neighbour_info(min_pixel, max_pixel, pix_list, threshold_image);
 
  SeFloat total_area = 0.0;
  SeFloat bad_area = 0;
  SeFloat full_area = 0;
 
  // iterate over the aperture pixels
  for (int pixel_y = min_pixel.m_y; pixel_y <= max_pixel.m_y; pixel_y++) {
    for (int pixel_x = min_pixel.m_x; pixel_x <= max_pixel.m_x; pixel_x++) {
 
      // get the area coverage and continue if there is overlap
      auto area = aperture->getArea(centroid_x, centroid_y, pixel_x, pixel_y);
      if (area == 0) {
        continue;
      }
 
      total_area += area;
 
      full_area += neighbour_info.isNeighbourObjectPixel(pixel_x, pixel_y);
      bad_area += (var_cutout->getValue(pixel_x - min_pixel.m_x, pixel_y - min_pixel.m_y) >
                   variance_threshold);
    }
  }
 
  // check/set the bad area flag
  if (total_area > 0 && bad_area / total_area > BADAREA_THRESHOLD_APER)
    flag |= Flags::BIASED;
 
  // check/set the crowded area flag
  if (total_area > 0 && full_area / total_area > CROWD_THRESHOLD_APER)
    flag |= Flags::NEIGHBORS;
 
  return flag;
}
 
} // end of namespace SourceXtractor