@misc{indiciaef830f29a9548,
  title = {Edge extraction by active defocusing.},
  author = {Q M Zhu and Y Y Hung and S H Tang and D H Shi},
  year = {1991},
  doi = {10.1163/156856891x00029},
  url = {https://pubmed.ncbi.nlm.nih.gov/1751426/},
  note = {Source identifier: 1751426}
}