Patent ID: 8922604

Claim:
An image display device with a function of controlling a backlight luminance and a function of displaying one or more rectangular subscreens indicating one or more input images, in a display screen, comprising: a display panel including a plurality of display elements for controlling light transmittances, the display panel having the display screen; a backlight including a plurality of light sources; a screen control section for determining for each of the one or more subscreens either a position in which to arrange the subscreen in the display screen or a size of the subscreen, or both; a screen generation section for generating a combined input image in which the one or more input images are arranged in either or both of the position and the size determined by the screen control section; an emission luminance calculation section for setting a plurality of areas corresponding to the light sources within the combined input image, and obtaining emission luminance data on the basis of the combined input image for each of the set areas, the emission luminance data indicating luminances upon emission of the light sources corresponding to the area; a display data calculation section for obtaining display data for controlling the light transmittances of the display elements, on the basis of the combined input image and the emission luminance data obtained by the emission luminance calculation section; a panel driver circuit for outputting signals for controlling the light transmittances of the display elements to the display panel, on the basis of the display data; and a backlight driver circuit for outputting signals for controlling the luminances of the light sources to the backlight, on the basis of the emission luminance data, wherein, the screen control section sets either the position in which to arrange the subscreen or the size of the subscreen, or both, such that a boundary of the subscreen coincides with a boundary of any one of the areas, the screen control section sets a predetermined or externally received arrangement position for the subscreen on the basis of a result of performing either or both of computation for determining a shorter moving distance between a left movement and a right movement in a horizontal moving direction within the display screen or computation for determining a shorter moving distance between an up movement and a down movement in a vertical moving direction within the display screen, so as to cause the boundary of the subscreen to coincide with the boundary of the area, and without changing a position of the boundary of the subscreen caused to coincide with the boundary of the area by moving the arrangement position of the subscreen, the screen control section sets the size of the subscreen on the basis of a result of performing computation for reducing the size such that an opposite boundary of the subscreen coincides with a corresponding opposite boundary of the area.