A display apparatus, comprising: a display including a plurality of display modules; wherein each display module includes pixels, the pixels being LED pixels; and a processor configured to drive the pixels and to: measure a first voltage applied to a resistor connected to reference pixels by a reverse current flowing through the reference pixels operating in a light reception mode by a light emitted from first adjacent pixels that are adjacent to the reference pixels, the reference pixels being pixels arranged on an outer horizontal line or an outer vertical line from among pixels included in a display module, the first adjacent pixels being pixels arranged on an adjacent line to the reference pixels, the first adjacent pixels and the reference pixels being included in a first display module of the plurality of display modules, wherein the processor controls the reference pixels to be operated in the light reception mode by applying a reverse voltage to the reference pixels, measure a second voltage applied to the resistor connected to reference pixels by a reverse current flowing through the reference pixels operating in the light reception mode by a light emitted from second adjacent pixels that are adjacent to the reference pixels, the second adjacent pixels being pixels arranged on an adjacent line to the reference pixels, the second adjacent pixels being included in one or more display modules that are adjacent to the first display module, determine whether a difference between the measured first voltage and the measured second voltage is larger than or equal to a predetermined threshold value, and adjust a gain of a current with respect to the second adjacent pixels based on amplitudes of the first voltage and the second voltage when the processor determines that the determined difference is larger than or equal to the predetermined threshold value, thereby removing a seam formed in the area between the first adjacent pixels and the second adjacent pixels. a display including a plurality of display modules; wherein each display module includes pixels, the pixels being LED pixels; and a processor configured to drive the pixels and to: measure a first voltage applied to a resistor connected to reference pixels by a reverse current flowing through the reference pixels operating in a light reception mode by a light emitted from first adjacent pixels that are adjacent to the reference pixels, the reference pixels being pixels arranged on an outer horizontal line or an outer vertical line from among pixels included in a display module, the first adjacent pixels being pixels arranged on an adjacent line to the reference pixels, the first adjacent pixels and the reference pixels being included in a first display module of the plurality of display modules, wherein the processor controls the reference pixels to be operated in the light reception mode by applying a reverse voltage to the reference pixels, measure a second voltage applied to the resistor connected to reference pixels by a reverse current flowing through the reference pixels operating in the light reception mode by a light emitted from second adjacent pixels that are adjacent to the reference pixels, the second adjacent pixels being pixels arranged on an adjacent line to the reference pixels, the second adjacent pixels being included in one or more display modules that are adjacent to the first display module, determine whether a difference between the measured first voltage and the measured second voltage is larger than or equal to a predetermined threshold value, and adjust a gain of a current with respect to the second adjacent pixels based on amplitudes of the first voltage and the second voltage when the processor determines that the determined difference is larger than or equal to the predetermined threshold value, thereby removing a seam formed in the area between the first adjacent pixels and the second adjacent pixels.