An electronic apparatus comprising: a memory storing a reference image (400, 510, 520, 710, 810, 820) being composed of at least one region (410, 420, 430), each region comprising a plurality of gradation regions (411, 412, 413, 421, 422, 423, 431, 432, 433, 811, 811', 812, 812', 813, 813', 821, 821', 822, 822', 823, 823', 831, 831', 832, 832', 833, 833',...), each gradation region of a respective region having a different gradation value; a communicator configured to transmit the reference image (400, 510, 520, 710, 810, 820) to a display device; a camera configured to photograph an image of (i) the display device that outputs the reference image (400, 510, 520, 710, 810, 820) and (ii) a background area surrounding the display device; and characterised in that the electronic apparatus comprises a processor configured to: obtain correction data for correcting gradation values of the photographed image by comparing the gradation values of each of the plurality of gradation regions (411, 412, 413, 421, 422, 423, 431, 432, 433, 811, 811', 812, 812', 813, 813', 821, 821', 822, 822', 823, 823', 831, 831', 832, 832', 833, 833',...) included in the photographed image and the gradation values of each of the respective corresponding plurality of gradation regions (411, 412, 413, 421, 422, 423, 431, 432, 433, 811, 811', 812, 812', 813, 813', 821, 821', 822, 822', 823, 823', 831, 831', 832, 832', 833, 833',...) included in the stored reference image (400, 510, 520, 710, 810, 820), generate a background image corresponding to the background area surrounding the display device from the photographed image, correct the generated background image based on the obtained correction data, and control the display device to output the corrected background image. a memory storing a reference image (400, 510, 520, 710, 810, 820) being composed of at least one region (410, 420, 430), each region comprising a plurality of gradation regions (411, 412, 413, 421, 422, 423, 431, 432, 433, 811, 811', 812, 812', 813, 813', 821, 821', 822, 822', 823, 823', 831, 831', 832, 832', 833, 833',...), each gradation region of a respective region having a different gradation value; a communicator configured to transmit the reference image (400, 510, 520, 710, 810, 820) to a display device; a camera configured to photograph an image of (i) the display device that outputs the reference image (400, 510, 520, 710, 810, 820) and (ii) a background area surrounding the display device; and characterised in that the electronic apparatus comprises a processor configured to: obtain correction data for correcting gradation values of the photographed image by comparing the gradation values of each of the plurality of gradation regions (411, 412, 413, 421, 422, 423, 431, 432, 433, 811, 811', 812, 812', 813, 813', 821, 821', 822, 822', 823, 823', 831, 831', 832, 832', 833, 833',...) included in the photographed image and the gradation values of each of the respective corresponding plurality of gradation regions (411, 412, 413, 421, 422, 423, 431, 432, 433, 811, 811', 812, 812', 813, 813', 821, 821', 822, 822', 823, 823', 831, 831', 832, 832', 833, 833',...) included in the stored reference image (400, 510, 520, 710, 810, 820), generate a background image corresponding to the background area surrounding the display device from the photographed image, correct the generated background image based on the obtained correction data, and control the display device to output the corrected background image. obtain correction data for correcting gradation values of the photographed image by comparing the gradation values of each of the plurality of gradation regions (411, 412, 413, 421, 422, 423, 431, 432, 433, 811, 811', 812, 812', 813, 813', 821, 821', 822, 822', 823, 823', 831, 831', 832, 832', 833, 833',...) included in the photographed image and the gradation values of each of the respective corresponding plurality of gradation regions (411, 412, 413, 421, 422, 423, 431, 432, 433, 811, 811', 812, 812', 813, 813', 821, 821', 822, 822', 823, 823', 831, 831', 832, 832', 833, 833',...) included in the stored reference image (400, 510, 520, 710, 810, 820), generate a background image corresponding to the background area surrounding the display device from the photographed image, correct the generated background image based on the obtained correction data, and control the display device to output the corrected background image.