A light guide plate has a back face provided with a first light diffusion pattern which tends to get denser according to an increasing distance from a primary light source. The light guide plate has an emission face provided with a second light diffusion pattern covering rate of is the largest at an approximately center portion (particular partial region) of the emission face. The first and second light diffusion patterns consist of a great number of fine light diffusion elements, respectively. Each fine light diffusion element of the second light diffusion pattern has a smaller size as compared with that of the first light diffusion pattern. The emission face of the light guide plate has an effective emission area to provide an emission light which is supplied to an LCD panel or other objects to be illuminated, via a light control member such as prism sheet. The approximately center portion and/or other one or more particular partial regions in the emission face show an intentionally heightened brightness. This enables an image display unit to have an approximately center portion and/or other one or more particular partial regions which display a brightness-emphasized image. Such an emphasis display technique is suitably applied to devices such as digital still cameras or digital video cameras which employ image-screen-center-portion focusing.□