A three-dimensional, 3D, image providing method comprising: detecting an eye location of a viewer), wherein detecting the eye location of the viewer comprises detecting a location of a right eye and a location of a left eye of the viewer; and providing a 3D image based on the detected eye location, wherein the providing of the 3D image comprises: determining an image pixel value corresponding to a display pixel (215; 615) included in a display panel (210; 610; 810; 1140); determining a luminance weight corresponding to the display pixel (215; 615) based on a ray direction of a ray output from the display pixel (215; 615) and the detected eye location, wherein the ray output from the display pixel (215; 615) is transmitted in a certain direction through a 3D optical device, wherein the determining of the luminance weight comprises determining the luminance weight based on at least one of a first reference value corresponding to a distance between a pass-through point of the ray direction and the location of the left eye of the viewer, and a second reference value corresponding to a distance between the pass-through point and the location of the right eye of the viewer, wherein the pass-through point of the ray direction is a location where a ray of the ray direction crosses a line passing through the location of the left eye and the location of the right eye; applying the determined luminance weight to the image pixel value corresponding to the display pixel (215; 615); and outputting, through the display pixel (215; 615), the image pixel value with the determined luminance weight applied thereto. detecting an eye location of a viewer), wherein detecting the eye location of the viewer comprises detecting a location of a right eye and a location of a left eye of the viewer; and providing a 3D image based on the detected eye location, wherein the providing of the 3D image comprises: determining an image pixel value corresponding to a display pixel (215; 615) included in a display panel (210; 610; 810; 1140); determining a luminance weight corresponding to the display pixel (215; 615) based on a ray direction of a ray output from the display pixel (215; 615) and the detected eye location, wherein the ray output from the display pixel (215; 615) is transmitted in a certain direction through a 3D optical device, wherein the determining of the luminance weight comprises determining the luminance weight based on at least one of a first reference value corresponding to a distance between a pass-through point of the ray direction and the location of the left eye of the viewer, and a second reference value corresponding to a distance between the pass-through point and the location of the right eye of the viewer, wherein the pass-through point of the ray direction is a location where a ray of the ray direction crosses a line passing through the location of the left eye and the location of the right eye; applying the determined luminance weight to the image pixel value corresponding to the display pixel (215; 615); and outputting, through the display pixel (215; 615), the image pixel value with the determined luminance weight applied thereto. determining an image pixel value corresponding to a display pixel (215; 615) included in a display panel (210; 610; 810; 1140); determining a luminance weight corresponding to the display pixel (215; 615) based on a ray direction of a ray output from the display pixel (215; 615) and the detected eye location, wherein the ray output from the display pixel (215; 615) is transmitted in a certain direction through a 3D optical device, wherein the determining of the luminance weight comprises determining the luminance weight based on at least one of a first reference value corresponding to a distance between a pass-through point of the ray direction and the location of the left eye of the viewer, and a second reference value corresponding to a distance between the pass-through point and the location of the right eye of the viewer, wherein the pass-through point of the ray direction is a location where a ray of the ray direction crosses a line passing through the location of the left eye and the location of the right eye; applying the determined luminance weight to the image pixel value corresponding to the display pixel (215; 615); and outputting, through the display pixel (215; 615), the image pixel value with the determined luminance weight applied thereto.