title: Visibility of continuous luminance gradients.
mesh_terms: D005556:Form Perception; D006801:Humans; D008027:Light; D009949:Orientation; D010783:Photometry; D011680:Pupil / Q000502:physiology; D012160:Retina / Q000502:physiology; D013028:Space Perception; D014785:Vision, Ocular