@article{ cadik08perceptual,
  author    = {Martin {\v{C}}ad\'{i}k},
  title     = {Perceptual Evaluation of Color-to-Grayscale Image Conversions},
  journal   = {Comput. Graph. Forum},
  volume    = {27},
  number    = {7},
  year      = {2008},
  pages     = {1745-1754},
}