A calibrating device includes a memory and a processor. The memory is configured to store at least one computer readable instruction. The processor is electrically coupled to the memory, and configured to access and execute the at least one computer readable instruction to: analyze an image of a target region which a seam between two LED panels disposed side by side is in, to obtain characteristic data associated with the seam; compare the characteristic data associated with the seam with a predetermined value to generate a comparison result; and adjust grayscale data of pixels which are arranged in two lines of the two LED panels and adjacent to the seam, based on the comparison result, for adjusting luminance-chromaticity of the pixels, wherein the two lines are in a first direction or a second direction, and the first direction is perpendicular to the second direction.