A privacy-mode backlight includes a light guide configured to guide light having a predetermined collimation factor orthogonal to a length of the light guide and a plurality of scattering line elements arranged along the light guide length. Scattering line elements of the scattering line element plurality are configured to scatter out through an emission surface of the light guide a portion of the guided light as emitted light having an illumination beamwidth in the orthogonal direction determined by the collimation factor. The privacy-mode backlight further includes a directional optical diffuser configured to provide directional diffusion of the emitted light in a direction corresponding to the light guide length. The directional diffusion may provide uniform illumination in the light guide length direction. A privacy display further includes an array of light valves configured to modulate the emitted light to provide a private image.