To cite package ‘colocr’ in publications use:

  Ahmed M, Lai TH, Kim DR. 2019. colocr: an R package for conducting
  co-localization analysis on fluorescence microscopy images. PeerJ
  7:e7255 https://doi.org/10.7717/peerj.7255

A BibTeX entry for LaTeX users is

  @Article{,
    title = {colocr: an R package for conducting co-localization analysis on fluorescence microscopy images},
    author = {Mahmoud Ahmed and Trang Huyen Lai and Deok Ryong Kim},
    year = {2019},
    journal = {PeerJ},
    doi = {10.7717/peerj.7255},
    volume = {7},
    pages = {e7255},
  }